Using ${ESHOP_EXTERNAL_DNS_NAME_OR_IP} from docker-compose.override.yml, as well. Notice that when using "localhost" from the browser URL using the MVC app, you'd need to use the 10.0.75.1 IP in a "Docker for Windows" environment.

Other than that, update the .env file with your IP or DNS name, and use that from the brower and the ${ESHOP_EXTERNAL_DNS_NAME_OR_IP} in all the docker-compose files.

.env

@@ -2,4 +2,5 @@
 # Compose expects each line in an env file to be in VAR=VAL format. Lines beginning with # (i.e. comments) are ignored, as are blank lines.
 # Note: Values present in the environment at runtime will always override those defined inside the .env file. Similarly, values passed via command-line arguments take precedence as well.
 
-ESHOP_EXTERNAL_DNS_NAME_OR_IP=192.168.88.248
+# localhost should be swapped to your real IP or DNS name, like 192.168.88.248, etc. if testing from remote browsers or mobile devices
+ESHOP_EXTERNAL_DNS_NAME_OR_IP=localhost

docker-compose.override.yml

@@ -1,5 +1,10 @@
 version: '2'
 
+# The default docker-compose.override file can use the "localhost" as the external name for testing web apps within the same dev machine. 
+# The ESHOP_EXTERNAL_DNS_NAME_OR_IP environment variable is taken, by default, from the ".env" file defined like ESHOP_EXTERNAL_DNS_NAME_OR_IP=localhost
+# but values present in the environment vars at runtime will always override those defined inside the .env file
+# An external IP or DNS name has to be used (instead localhost and the 10.0.75.1 IP) when testing the Web apps and the Xamarin apps from remote machines/devices using the same WiFi, for instance.
+
 services:
 
   basket.api:
@@ -16,7 +21,7 @@ services:
       - ASPNETCORE_ENVIRONMENT=Development
       - ASPNETCORE_URLS=http://0.0.0.0:5101
       - ConnectionString=Server=sql.data;Database=Microsoft.eShopOnContainers.Services.CatalogDb;User Id=sa;Password=Pass@word
-      - ExternalCatalogBaseUrl=http://localhost:5101    #Local: You need to open your local dev-machine firewall at range 5100-5105.  at range 5100-5105.
+      - ExternalCatalogBaseUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5101    #Local: You need to open your local dev-machine firewall at range 5100-5105.  at range 5100-5105.
     ports:
       - "5101:5101"
 
@@ -24,9 +29,9 @@ services:
     environment:
       - ASPNETCORE_ENVIRONMENT=Development
       - ASPNETCORE_URLS=http://0.0.0.0:5105
-      - SpaClient=http://localhost:5104
+      - SpaClient=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5104
       - ConnectionStrings__DefaultConnection=Server=sql.data;Database=Microsoft.eShopOnContainers.Service.IdentityDb;User Id=sa;Password=Pass@word 
-      - MvcClient=http://localhost:5100              #Local: You need to open your local dev-machine firewall at range 5100-5105.  
+      - MvcClient=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5100              #Local: You need to open your local dev-machine firewall at range 5100-5105.  
     ports:
       - "5105:5105"
 
@@ -43,10 +48,10 @@ services:
     environment:
       - ASPNETCORE_ENVIRONMENT=Development
       - ASPNETCORE_URLS=http://0.0.0.0:5104
-      - CatalogUrl=http://localhost:5101
-      - OrderingUrl=http://localhost:5102
-      - IdentityUrl=http://localhost:5105              #Local: You need to open your local dev-machine firewall at range 5100-5105.  at range 5100-5105. 
-      - BasketUrl=http://localhost:5103                
+      - CatalogUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5101
+      - OrderingUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5102
+      - IdentityUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5105              #Local: You need to open your local dev-machine firewall at range 5100-5105.  at range 5100-5105. 
+      - BasketUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5103                
     ports:
       - "5104:5104"
 
@@ -56,8 +61,9 @@ services:
       - ASPNETCORE_URLS=http://0.0.0.0:5100
       - CatalogUrl=http://catalog.api:5101
       - OrderingUrl=http://ordering.api:5102
-      - IdentityUrl=http://10.0.75.1:5105              #Local: You need to open your local dev-machine firewall at range 5100-5105.  at range 5100-5105. 
       - BasketUrl=http://basket.api:5103
+      - IdentityUrl=http://10.0.75.1:5105        #Local:  Use 10.0.75.1 in a "Docker for Windows" environment, if using "localhost" from browser. 
+                                                 #Remote: Use ${ESHOP_EXTERNAL_DNS_NAME_OR_IP} if using external IP or DNS name from browser. 
     ports:
       - "5100:5100"
 

docker-compose.prod.yml

@@ -3,7 +3,8 @@ version: '2'
 # The Production docker-compose file has to have the external/real IPs or DNS names for the services 
 # The ESHOP_EXTERNAL_DNS_NAME_OR_IP environment variable is taken, by default, from the ".env" file defined like ESHOP_EXTERNAL_DNS_NAME_OR_IP=192.168.88.248
 # but values present in the environment vars at runtime will always override those defined inside the .env file
-# This configuration has to be used when testing the Web apps and the Xamarin apps from remote machines/devices using the same WiFi, for instance.
+# An external IP or DNS name has to be used when testing the Web apps and the Xamarin apps from remote machines/devices using the same WiFi, for instance.
+#
 # ASPNETCORE_ENVIRONMENT=Development just to get errors while testing. Could be set to "Production"
 #
 # You need to start it with the following CLI command: 
@@ -65,7 +66,7 @@ services:
       - ASPNETCORE_URLS=http://0.0.0.0:5100
       - CatalogUrl=http://catalog.api:5101
       - OrderingUrl=http://ordering.api:5102
-      - IdentityUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5105              #Local: You need to open your host's firewall at range 5100-5105.  at range 5100-5105. 
+      - IdentityUrl=http://${ESHOP_EXTERNAL_DNS_NAME_OR_IP}:5105     #Local: Use ${ESHOP_EXTERNAL_DNS_NAME_OR_IP}, if using external IP or DNS name from browser.          
       - BasketUrl=http://basket.api:5103
     ports:
       - "5100:5100"