I bit the bullet and bought a wireless router (WRT54G V8). It set up very easily, and I have the security set so I don't THINK I'm being leeched.
With the Wii in "amber" sleep mode, I noticed that my wired PC connection would slow down and eventually lock up...resetting the router would fix this. I checked around, and changed the MTU setting from auto to manual and thought this worked...until I noticed that the Wii was completely off (red light).
After testing it in standby again...the slowdowns started up again.
I tried Google with no love, and not a lot of help on Linksys's or Nintendo's website either.
Is there a setting that I'm missing that could cause an active wireless connection to slowly leech more and more bandwidth until I have to reset?
When the Wii is off...I have no problems. So I think the wireless is the problem.
Slow to the point of locking up. I found a couple of threads on Linksys's forums after digging some more. There are several people with the same problem, and they had a few suggestions to try.
It's some quirk that only happens when the wireless connection is activated. Once it does lock, you have to reset the router by disconnecting the power to get back to "normal". Plus it's only happening with the newer versions, v6 & v8. Older versions of the same router work fine.
I'll let you know how the possible fixes turn out.
***Sorry for late update...the update to the firmware fixed the problem***
The part Guru is talking about is the PRAM battery. Instructions for resetting it can be found here. But, given the symptoms, you probably will have better luck trying a reset of the "Cuda" a.k.a. the Power Management Unit.