Networking problem with Linksys wireless-b router

I have 3 computers networked on a linksys wireless-b router (two wireless, one wired). From the beginning I have been having problems staying connected. I've had to tinker with my MTU by changing the value from 1500 to 1300, and then either disabling or enabling it whenever I lose connection. Now that doesn't seem to be doing anything. One of my computers "cannot contact dhcp." I'm wondering if someone could provide a few words of wisdow for my problem.

 

Can you be a little more specific as to what you mean by "problems staying connected "? MTU problems usually relate to internet connection problems, whereas being unable to reach a DHCP server usually refers to a local network problem (that is you cannot connect to resources within your network).

Are you having problems connecting to your network? Or can the computers connect to the network, but then they cannot connect to the internet?