Can't connect to my server via client

[GordonJ]

As said, I can't connect to my server via my client, however, others can. By client, I'm also referring to the Garry's Mod server we've set up, so I'm unable to connect to the server via Garry's Mod. I can essentially connect through any means other than Garry's Mod. On my Garry's Mod client, I can connect to any other server, however just not my server. Other people can also join the server. Below are the methods I have already attempted before.

No addons subscribed to
Resetting/Wiping the server for a new install
Wiping/reinstalling my Garry's Mod
Restarted my PC
Attempted on a separate computer (and same issue)
Attempted to restart my modem
Attempted to turn off my firewall, and my Malwarebytes antivirus


Attempted to ping the server (which worked)
Connecting to the FTP works
Connecting via PuTTY works

My sneaking suspicion is that the Garry's Mod blacklisting system has somehow blacklisted the IP for me personally (because as I said others can join and I can't access it via either of my computers.

[Naleksuh]

To clarify, you are using a managed Garry's Mod server and not an installation on VDS, right?

What happens when you type "listip" into the server console?