mousiopeyou can have ppl entering your listen server if you port forward correctly for that (i guess you already have that one covered)
im guessing you have something in your dedicated server cfg with the wrong value? maybe sv_lan ? or you port forwarded incorrectly for that (not sure if it uses different ports than the listen one)
try a different tutorial theres a bunch, i remember using a one click tool that created the server and updated sourcemod and metamod on his own
Oh, I haven't heard about a one click tool, I'm going to check that out, thanks.