Did you replace with a Linksys router? Specifically BEFSR41? Return it, they are defective and cannot be made to reliably work, even with new dnloaded firmware. There are pages and pages of folks you can find in usergroups who have collectively spent thousands of hours trying. I bot a $19 Netgear router and it worked on first plug in and has stayed working for 8 months flawlessly. (I am moderatley, not mega-skilled, btw)
Agree that Linksys is mostly crap that never works like the manual says it should.
Netgear is OK.
I have had excellent luck with products from D-Link, which is probably the cheapest of the big three networking equipment makers. It is also the most Macintosh-friendly.
-ccm
The Linksys router we originally had was a BEFSR41 ~ the new one is GEB-blah,blah, blah.
We had the original on for over eight years without any problems.