Cant Login

[Lm2004]

Ok, im sorry for this post, but all the searchs i have done confuze me, alot, and some links to this error dont even explain it =(

But when i run my server and then i log on from my other pc, i cant see it at all!!!, 100% nothing, my server isnt there at all, i have a firewall and i dono how to turn it off, i have about 4 PC's connected to this router and i have an actiontec router, if anyone knows what to do, please post, sorry again for the post, but someone needs to make a clear tutorial on this and not take the lazy way and link to a thread that has nothing to do with it, or has been edit'd into oblivion =/

thanks in advance, and sorry once again.