Windows Garrysmod Startup Error

Having a issue when recieving this when starting my server on my dedicated server
“Warning! Singleplayer mode not available on dedicated server.” Any ideas how I can fix this?

Thanks!

Commandline? Installed trough hldsupdatetool?

Maxplayers needs to be higher then 1.

Changing max players worked but cannot see it online the server is not behind a firewall so I dont know whats up at the moment.

Well, that can have a lot of reasons. Take a look at routers portforwarding.
https://support.steampowered.com/kb_article.php?ref=8571-GLVN-8711
However, I doubt that’s complete. I think the masterserver is using another port for communication.