diff --git a/changelog.d/6095.bugfix b/changelog.d/6095.bugfix
new file mode 100644
index 0000000000..11110bfa08
--- /dev/null
+++ b/changelog.d/6095.bugfix
@@ -0,0 +1 @@
+Correct .well-known/matrix/client handling for server_names which include ports.
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt
index 867e066e60..82f39806c0 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/MatrixPatterns.kt
@@ -177,7 +177,7 @@ object MatrixPatterns {
      * - "@alice:domain.org".getDomain() will return "domain.org"
      * - "@bob:domain.org:3455".getDomain() will return "domain.org:3455"
      */
-    fun String.getDomain(): String {
+    fun String.getServerName(): String {
         if (BuildConfig.DEBUG && !isUserId(this)) {
             // They are some invalid userId localpart in the wild, but the domain part should be there anyway
             Timber.w("Not a valid user ID: $this")
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/auth/DefaultAuthenticationService.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/auth/DefaultAuthenticationService.kt
index f1cfe3fee5..02dfce04b5 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/auth/DefaultAuthenticationService.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/auth/DefaultAuthenticationService.kt
@@ -20,7 +20,7 @@ import android.net.Uri
 import dagger.Lazy
 import okhttp3.OkHttpClient
 import org.matrix.android.sdk.api.MatrixPatterns
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.auth.AuthenticationService
 import org.matrix.android.sdk.api.auth.data.Credentials
 import org.matrix.android.sdk.api.auth.data.HomeServerConnectionConfig
@@ -381,7 +381,7 @@ internal class DefaultAuthenticationService @Inject constructor(
 
         return getWellknownTask.execute(
                 GetWellknownTask.Params(
-                        domain = matrixId.getDomain(),
+                        domain = matrixId.getServerName().substringBeforeLast(":"),
                         homeServerConnectionConfig = homeServerConnectionConfig.orWellKnownDefaults()
                 )
         )
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/homeserver/GetHomeServerCapabilitiesTask.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/homeserver/GetHomeServerCapabilitiesTask.kt
index e9097e4d03..b1a518724c 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/homeserver/GetHomeServerCapabilitiesTask.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/homeserver/GetHomeServerCapabilitiesTask.kt
@@ -17,7 +17,7 @@
 package org.matrix.android.sdk.internal.session.homeserver
 
 import com.zhuinden.monarchy.Monarchy
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.auth.data.HomeServerConnectionConfig
 import org.matrix.android.sdk.api.auth.wellknown.WellknownResult
 import org.matrix.android.sdk.api.extensions.orFalse
@@ -93,10 +93,14 @@ internal class DefaultGetHomeServerCapabilitiesTask @Inject constructor(
             }
         }.getOrNull()
 
+        // Domain may include a port (eg, matrix.org:8080)
+        // Per https://spec.matrix.org/latest/client-server-api/#well-known-uri we should extract the hostname from the server name
+        // So we take everything before the last : as the domain for the well-known task.
+        // NB: This is not always the same endpoint as capabilities / mediaConfig uses.
         val wellknownResult = runCatching {
             getWellknownTask.execute(
                     GetWellknownTask.Params(
-                            domain = userId.getDomain(),
+                            domain = userId.getServerName().substringBeforeLast(":"),
                             homeServerConnectionConfig = homeServerConnectionConfig
                     )
             )
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/permalinks/ViaParameterFinder.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/permalinks/ViaParameterFinder.kt
index 0f667c65df..edc45fe945 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/permalinks/ViaParameterFinder.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/permalinks/ViaParameterFinder.kt
@@ -16,7 +16,7 @@
 
 package org.matrix.android.sdk.internal.session.permalinks
 
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.query.QueryStringValue
 import org.matrix.android.sdk.api.session.events.model.EventType
 import org.matrix.android.sdk.api.session.events.model.toModel
@@ -55,9 +55,9 @@ internal class ViaParameterFinder @Inject constructor(
     }
 
     fun computeViaParams(userId: String, roomId: String, max: Int): List<String> {
-        val userHomeserver = userId.getDomain()
+        val userHomeserver = userId.getServerName()
         return getUserIdsOfJoinedMembers(roomId)
-                .map { it.getDomain() }
+                .map { it.getServerName() }
                 .groupBy { it }
                 .mapValues { it.value.size }
                 .toMutableMap()
@@ -92,7 +92,7 @@ internal class ViaParameterFinder @Inject constructor(
                 .orEmpty()
                 .toSet()
 
-        return userThatCanInvite.map { it.getDomain() }
+        return userThatCanInvite.map { it.getServerName() }
                 .groupBy { it }
                 .mapValues { it.value.size }
                 .toMutableMap()
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/alias/RoomAliasAvailabilityChecker.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/alias/RoomAliasAvailabilityChecker.kt
index 7c137a8102..fa19b4f9cf 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/alias/RoomAliasAvailabilityChecker.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/alias/RoomAliasAvailabilityChecker.kt
@@ -16,7 +16,7 @@
 
 package org.matrix.android.sdk.internal.session.room.alias
 
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.failure.Failure
 import org.matrix.android.sdk.api.session.room.alias.RoomAliasError
 import org.matrix.android.sdk.internal.di.UserId
@@ -65,6 +65,6 @@ internal class RoomAliasAvailabilityChecker @Inject constructor(
     }
 
     companion object {
-        internal fun String.toFullLocalAlias(userId: String) = "#" + this + ":" + userId.getDomain()
+        internal fun String.toFullLocalAlias(userId: String) = "#" + this + ":" + userId.getServerName()
     }
 }
diff --git a/vector/src/main/java/im/vector/app/features/login/LoginViewModel.kt b/vector/src/main/java/im/vector/app/features/login/LoginViewModel.kt
index c9cb4612a8..1b08d2a86f 100644
--- a/vector/src/main/java/im/vector/app/features/login/LoginViewModel.kt
+++ b/vector/src/main/java/im/vector/app/features/login/LoginViewModel.kt
@@ -36,7 +36,7 @@ import im.vector.app.core.resources.StringProvider
 import im.vector.app.core.utils.ensureTrailingSlash
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.auth.AuthenticationService
 import org.matrix.android.sdk.api.auth.HomeServerHistoryService
 import org.matrix.android.sdk.api.auth.data.HomeServerConnectionConfig
@@ -607,7 +607,7 @@ class LoginViewModel @AssistedInject constructor(
                         identityServerUri = wellKnownPrompt.identityServerUrl?.let { Uri.parse(it) }
                 )
                 ?: HomeServerConnectionConfig(
-                        homeServerUri = Uri.parse("https://${action.username.getDomain()}"),
+                        homeServerUri = Uri.parse("https://${action.username.getServerName()}"),
                         homeServerUriBase = Uri.parse(wellKnownPrompt.homeServerUrl),
                         identityServerUri = wellKnownPrompt.identityServerUrl?.let { Uri.parse(it) }
                 )
diff --git a/vector/src/main/java/im/vector/app/features/login2/LoginViewModel2.kt b/vector/src/main/java/im/vector/app/features/login2/LoginViewModel2.kt
index e72e3a1790..6b9d255937 100644
--- a/vector/src/main/java/im/vector/app/features/login2/LoginViewModel2.kt
+++ b/vector/src/main/java/im/vector/app/features/login2/LoginViewModel2.kt
@@ -38,7 +38,7 @@ import im.vector.app.features.login.LoginMode
 import im.vector.app.features.login.ReAuthHelper
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.auth.AuthenticationService
 import org.matrix.android.sdk.api.auth.HomeServerHistoryService
 import org.matrix.android.sdk.api.auth.data.HomeServerConnectionConfig
@@ -640,7 +640,7 @@ class LoginViewModel2 @AssistedInject constructor(
         }
         viewEvent?.let { _viewEvents.post(it) }
 
-        val urlFromUser = action.username.getDomain()
+        val urlFromUser = action.username.getServerName()
         setState {
             copy(
                     isLoading = false,
diff --git a/vector/src/main/java/im/vector/app/features/onboarding/DirectLoginUseCase.kt b/vector/src/main/java/im/vector/app/features/onboarding/DirectLoginUseCase.kt
index 171d8f7bb5..3014b199b4 100644
--- a/vector/src/main/java/im/vector/app/features/onboarding/DirectLoginUseCase.kt
+++ b/vector/src/main/java/im/vector/app/features/onboarding/DirectLoginUseCase.kt
@@ -20,7 +20,7 @@ import im.vector.app.R
 import im.vector.app.core.extensions.andThen
 import im.vector.app.core.resources.StringProvider
 import im.vector.app.features.onboarding.OnboardingAction.LoginOrRegister
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.auth.AuthenticationService
 import org.matrix.android.sdk.api.auth.data.HomeServerConnectionConfig
 import org.matrix.android.sdk.api.auth.wellknown.WellknownResult
@@ -75,7 +75,7 @@ class DirectLoginUseCase @Inject constructor(
     )
 
     private fun fallbackConfig(action: LoginOrRegister, wellKnownPrompt: WellknownResult.Prompt) = HomeServerConnectionConfig(
-            homeServerUri = uriFactory.parse("https://${action.username.getDomain()}"),
+            homeServerUri = uriFactory.parse("https://${action.username.getServerName()}"),
             homeServerUriBase = uriFactory.parse(wellKnownPrompt.homeServerUrl),
             identityServerUri = wellKnownPrompt.identityServerUrl?.let { uriFactory.parse(it) }
     )
diff --git a/vector/src/main/java/im/vector/app/features/raw/wellknown/ElementWellKnownExt.kt b/vector/src/main/java/im/vector/app/features/raw/wellknown/ElementWellKnownExt.kt
index 4dd5a68673..91269cb114 100644
--- a/vector/src/main/java/im/vector/app/features/raw/wellknown/ElementWellKnownExt.kt
+++ b/vector/src/main/java/im/vector/app/features/raw/wellknown/ElementWellKnownExt.kt
@@ -16,14 +16,14 @@
 
 package im.vector.app.features.raw.wellknown
 
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.auth.data.SessionParams
 import org.matrix.android.sdk.api.extensions.tryOrNull
 import org.matrix.android.sdk.api.raw.RawService
 
 suspend fun RawService.getElementWellknown(sessionParams: SessionParams): ElementWellKnown? {
     // By default we use the domain of the userId to retrieve the .well-known data
-    val domain = sessionParams.userId.getDomain()
+    val domain = sessionParams.userId.getServerName()
     return tryOrNull { getWellknown(domain) }
             ?.let { ElementWellKnownMapper.from(it) }
 }
diff --git a/vector/src/main/java/im/vector/app/features/roomdirectory/createroom/CreateRoomViewModel.kt b/vector/src/main/java/im/vector/app/features/roomdirectory/createroom/CreateRoomViewModel.kt
index 1994de396f..f1306d9851 100644
--- a/vector/src/main/java/im/vector/app/features/roomdirectory/createroom/CreateRoomViewModel.kt
+++ b/vector/src/main/java/im/vector/app/features/roomdirectory/createroom/CreateRoomViewModel.kt
@@ -35,7 +35,7 @@ import im.vector.app.features.raw.wellknown.getElementWellknown
 import im.vector.app.features.raw.wellknown.isE2EByDefault
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.extensions.orFalse
 import org.matrix.android.sdk.api.extensions.tryOrNull
 import org.matrix.android.sdk.api.raw.RawService
@@ -98,7 +98,7 @@ class CreateRoomViewModel @AssistedInject constructor(
     private fun initHomeServerName() {
         setState {
             copy(
-                    homeServerName = session.myUserId.getDomain()
+                    homeServerName = session.myUserId.getServerName()
             )
         }
     }
diff --git a/vector/src/main/java/im/vector/app/features/roomdirectory/picker/RoomDirectoryListCreator.kt b/vector/src/main/java/im/vector/app/features/roomdirectory/picker/RoomDirectoryListCreator.kt
index 90283de77c..a168ea749c 100644
--- a/vector/src/main/java/im/vector/app/features/roomdirectory/picker/RoomDirectoryListCreator.kt
+++ b/vector/src/main/java/im/vector/app/features/roomdirectory/picker/RoomDirectoryListCreator.kt
@@ -20,7 +20,7 @@ import im.vector.app.R
 import im.vector.app.core.resources.StringArrayProvider
 import im.vector.app.features.roomdirectory.RoomDirectoryData
 import im.vector.app.features.roomdirectory.RoomDirectoryServer
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.session.Session
 import org.matrix.android.sdk.api.session.room.model.thirdparty.ThirdPartyProtocol
 import javax.inject.Inject
@@ -37,7 +37,7 @@ class RoomDirectoryListCreator @Inject constructor(
         val protocols = ArrayList<RoomDirectoryData>()
 
         // Add user homeserver name
-        val userHsName = session.myUserId.getDomain()
+        val userHsName = session.myUserId.getServerName()
 
         // Add default protocol
         protocols.add(
diff --git a/vector/src/main/java/im/vector/app/features/roomprofile/alias/RoomAliasViewModel.kt b/vector/src/main/java/im/vector/app/features/roomprofile/alias/RoomAliasViewModel.kt
index 2641eb4184..a66ef9a659 100644
--- a/vector/src/main/java/im/vector/app/features/roomprofile/alias/RoomAliasViewModel.kt
+++ b/vector/src/main/java/im/vector/app/features/roomprofile/alias/RoomAliasViewModel.kt
@@ -31,7 +31,7 @@ import im.vector.app.features.powerlevel.PowerLevelsFlowFactory
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.query.QueryStringValue
 import org.matrix.android.sdk.api.session.Session
 import org.matrix.android.sdk.api.session.events.model.EventType
@@ -96,7 +96,7 @@ class RoomAliasViewModel @AssistedInject constructor(@Assisted initialState: Roo
     private fun initHomeServerName() {
         setState {
             copy(
-                    homeServerName = session.myUserId.getDomain()
+                    homeServerName = session.myUserId.getServerName()
             )
         }
     }
diff --git a/vector/src/main/java/im/vector/app/features/spaces/create/CreateSpaceViewModel.kt b/vector/src/main/java/im/vector/app/features/spaces/create/CreateSpaceViewModel.kt
index 46da2f5826..99c9547042 100644
--- a/vector/src/main/java/im/vector/app/features/spaces/create/CreateSpaceViewModel.kt
+++ b/vector/src/main/java/im/vector/app/features/spaces/create/CreateSpaceViewModel.kt
@@ -35,7 +35,7 @@ import im.vector.app.core.resources.StringProvider
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import org.matrix.android.sdk.api.MatrixPatterns
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.session.Session
 import org.matrix.android.sdk.api.session.identity.IdentityServiceListener
 import org.matrix.android.sdk.api.session.room.AliasAvailabilityResult
@@ -66,7 +66,7 @@ class CreateSpaceViewModel @AssistedInject constructor(
         val identityServerUrl = identityService.getCurrentIdentityServerUrl()
         setState {
             copy(
-                    homeServerName = session.myUserId.getDomain(),
+                    homeServerName = session.myUserId.getServerName(),
                     canInviteByMail = identityServerUrl != null
             )
         }
diff --git a/vector/src/test/java/im/vector/app/features/onboarding/DirectLoginUseCaseTest.kt b/vector/src/test/java/im/vector/app/features/onboarding/DirectLoginUseCaseTest.kt
index 6021b755f4..1fed03b601 100644
--- a/vector/src/test/java/im/vector/app/features/onboarding/DirectLoginUseCaseTest.kt
+++ b/vector/src/test/java/im/vector/app/features/onboarding/DirectLoginUseCaseTest.kt
@@ -27,7 +27,7 @@ import kotlinx.coroutines.test.runTest
 import org.amshove.kluent.should
 import org.amshove.kluent.shouldBeEqualTo
 import org.junit.Test
-import org.matrix.android.sdk.api.MatrixPatterns.getDomain
+import org.matrix.android.sdk.api.MatrixPatterns.getServerName
 import org.matrix.android.sdk.api.auth.data.HomeServerConnectionConfig
 import org.matrix.android.sdk.api.auth.data.WellKnown
 import org.matrix.android.sdk.api.auth.wellknown.WellknownResult
@@ -38,7 +38,7 @@ private val A_WELLKNOWN_FAILED_WITH_CONTENT_RESULT = WellknownResult.FailPrompt(
 private val A_WELLKNOWN_FAILED_WITHOUT_CONTENT_RESULT = WellknownResult.FailPrompt(null, null)
 private val NO_HOMESERVER_CONFIG: HomeServerConnectionConfig? = null
 private val A_FALLBACK_CONFIG: HomeServerConnectionConfig = HomeServerConnectionConfig(
-        homeServerUri = FakeUri("https://${A_LOGIN_OR_REGISTER_ACTION.username.getDomain()}").instance,
+        homeServerUri = FakeUri("https://${A_LOGIN_OR_REGISTER_ACTION.username.getServerName()}").instance,
         homeServerUriBase = FakeUri(A_WELLKNOWN_SUCCESS_RESULT.homeServerUrl).instance,
         identityServerUri = null
 )