There are multiple errors involved here.
- As @calmh pointed out, apparently the service doesn’t even start because of a malformed address in
config.xml. - In your initial post, you said the browser refused to connect on port 9090, while your SSH command uses port 9092.
- If you run
syncthing cli errors showon your local device, you need to pass--gui-address, in your case the forwarded local portlocalhost:9092, and--gui-apikeywith the API key of the remote machine where syncthing runs. - If you run the same command on the remote machine and it shows connection refused, then Syncthing is indeed most probably not running.