Linksys WRT300N Wireless router problemer!

Hi.

As this is my first thread on this forum, I hope to receive helpfull information from you guys.

I have just bought this new Linksys WRT300N Wireless Router. I have been using Linksys WRT54G before and it worked without any problems on a home network with 3 wired computers and 1 wireless connected, sharing a printer installed on 1 of the wired computers. Now I have changed to Linksys WRT300N Wireless Router to get better performance with exactly the same group of computers and printer, where now only 1 computer is wired to the router and 2 of the forma wired computers now wireless with original PCI Linksys adapter.

Problem:
1. The network group has become very unstable, sometimes you can see the other computers sometimes not periodically changing from time to time without any reason reboot or change.
2. It is now completely impossible to get access to other computers in the group, even they are all completely shared.
3. Is is completely impossible to estabilish a connection to the shared network printer except from the computer where it as before still is installed through USB cable. Of course the printer stays invisible from the other computers in the network group.

Hope to have your help soon :)

Sincerely,
Christopher, Denmark