In a sad turn of events, my Wii can no longer connect to the Internets. The error I get when trying the connection test is code 51130. Some Googling suggested changing the network to mixed B+G mode helps, but for me, it has not.

Here are the other things I've since tried to remedy this problem, all to no avail:
- Power cycled the router (several times)
- Changed wireless channel (was 1 before when things were working, also tried 6 and 11)
- Disabled wireless MAC filter (Wii's MAC was in the allow list prior to that)
- Completely disabled security
- Manual IP/DNS settings on the Wii instead of DHCP
- Flashed router with OpenWRT firmware (instead of Tomato)
- Changed the MTU on the Wii from automatic to 1500 (1500 works fine on everything else on my network)

When the connection test runs, I see the Wii's MAC address show up in the router's "Device List" page, so I know the router can "see" the Wii. When trying to use DHCP, no DHCPREQUEST is shown in the router's syslog. All of my other wireless clients are okay, and can get a DHCP lease. The signal strength shown coming from the Wii's MAC address is very high.

Feeling like I tried everything, I tried to jump on an open wifi network in my neighborhood (albeit one with a low signal strength for me) and still didn't find happiness. That could be because the signal isn't strong enough, though.

My next move is to drag the Wii over to my girlfriend's house and see if it likes the network there. After that, I guess I'm stuck calling Nintendo support and dealing with the invariable "is the router on? is the wii on?" line of questioning. So, I figured I'd ask here to see if anyone's run into / heard of any wifi problems, or has any idea how I can go about troubleshooting this further without dealing with support.