Merge branch 'next' into 'next'

Add portforwarding + opening to the docs (+recommended extension fix)

See merge request famedly/conduit!356

.vscode/extensions.json

 {
     "recommendations": [
-        "matklad.rust-analyzer",
+        "rust-lang.rust-analyzer",
         "bungcip.better-toml",
         "ms-azuretools.vscode-docker",
         "eamodio.gitlens",

DEPLOY.md

@@ -58,6 +58,12 @@ ## Adding a Conduit user
 sudo adduser --system conduit --no-create-home
 ```
 
+## Forwarding ports in the firewall or the router
+
+Conduit uses the ports 443 and 8448 both of which need to be open in the firewall.
+
+If Conduit runs behind a router or in a container and has a different public IP address than the host system these public ports need to be forwarded directly or indirectly to the port mentioned in the config.
+
 ## Setting up a systemd service
 
 Now we'll set up a systemd service for Conduit, so it's easy to start/stop Conduit and set it to autostart when your
@@ -247,7 +253,8 @@ ## How do I know it works?
 $ curl https://your.server.name:8448/_matrix/client/versions
 ```
 
-- To check if your server can talk with other homeservers, you can use the [Matrix Federation Tester](https://federationtester.matrix.org/)
+- To check if your server can talk with other homeservers, you can use the [Matrix Federation Tester](https://federationtester.matrix.org/).
+  If you can register but cannot join federated rooms check your config again and also check if the port 8448 is open and forwarded correctly.
 
 # What's next?