Can't run my server in GMod 12...

Please understand that my server works in GMod 13, but not in GMod 12.

NOTE: I feel that this does not belong in the beta section, since it’s about GMod 12.

When I first ran my server on GMod 13, it became growing more and more popular. I decided to try and run my server on GMod 12, but my server never showed on the internet.

THings I’ve done:
Reset my Port Forward
Re-installed my GMod
Restart GMod

When i host on source i always need to go through the process of typing “sv_lan 0” into the console and restarting the map.