Were you having the same slow connection issues when the wired
router was connected? The wireless works fine, except very slow as
it my PC which is connected to the wired router.
my primary problem was a intermittent connection, that would
eventually fail, and often pull the other routers down with it. Then
I would have to reboot all the routers and set them up again.
Running a wired BEFSR41 with a wireless WRT54GS I had no problem. The
problems, for me, came when I hooked up WRT546 as my wireless router.
Of course I can use either the 54GS or the 546 as wired and wireless
but only the 54GS can see my LAN. It is a security to protect my LAN/data.
You know the unique Linksys way of resetting their routers to default?
Remove any CAT5/ . With it powered on you press the reset button and
hold it for a FULL 30 seconds.
Then release it and immediately pull the power on the Router.
Let it sit for 5 minutes.
Plug it in
It will be back at factory settings.
I would try that first.
If you do call Linksys they will want to know the model, version,
BIOS number, and serial. And best to call them after midnight which
is daytime for them