So, a few months ago, my Netgear wireless router went on the fritz with all of the wireless devices on my network, except one.
(An old dell M1210, A Toshiba laptop from the Vista era, and two iPhones).
My Toshiba netbook however, was fine. Obviously given it was a shitty Netgear wireless router the PS3 wouldn't connect either (a known issue).
So, I bought myself a shiny Linksys 610N.
I plugged that in and after a small amount of teething trouble (running in simultaneous mode didn't work out for me). I had a rock solid, stable wireless connection available to everything within my network.
Cue Tuesday last week - I got home and wireless was not working - attempting to connect to the network was simple met with "Cannot connect to (SSID)" if I were using the hated Intel ProSET wireless manager or just windows wireless manager stuck sitting on "Connecting to network" for an indefinite period.
Linksys's default firmware did not offer me sufficient diagnostic options, so I put DD-WRT on there. I also had a hope that it might solve my issue. It did not.
DD-WRT doesn't yet have a great deal of additional diagnotic capacity - but I could set up a remote syslog server which would help - but I'm short on the free time to get this up and running on Linux or Windows under my own steam.
Security wise I was using WPA2-Personal AES, but have since tried TKIP and WPA-Personal AES and TKIP.
My two main suspicions are: Someone has recently turned on a wireless router or wireless device (like an elcheapo phone) which is powerful enough to eat Wireless LAN signals regardless of channel. Or, the hardware might have failed.
The issue is that the Wireless LAN is discoverable only periodically. Can occasionally be successfully connected to. It then drops packets like crazy (around the 75% mark) and then the connection drops out.
If you think its interference you can try to force 5ghz dual band. Your older devices might not be compatible but you'll know for sure if it interference if they work. I know it sucks but swapping channels one by one might be an option. Deleting the wireless profiles on each device might be something you've tried already but if not you can try that.
Best thing would be to borrow a router from a friend, backup the config, test, then restore when you're done.
The 5ghz thing would be q grand idea but for the fact that I have no 5ghz devices. Unless iPhones can do 5ghz wireless n.
I shall borrow a router from work also.
Also I have changed my wireless channel to what seems to be the leave overlappy. Everyone except 2 people on 11, one on 4 and one on 1 is on 6 (of which there are about 5).
Sounds like you've covered quite a bit already, like Greenish said. It'd be odd to have more than one dead router/AP in a row, but stranger things have happened. I'd be more inclined to address possible interference issues first.
It sounds like you live in an apartment or an area where you're able to pick up additional wireless signals. Have you taken a sample of the networks present? I see you have some sort of tool or utility within the router that can tell you how many people are on each channel, but have you used a tool like NetStumbler to check out the area? You can also use the netsh command inside Windows to pull up all of the networks in range, signal strength, speeds available, etc.
Even if you hop channels you could still run into problems if there's a particularly strong signal in the area.
Also, be sure to check for any other devices that operate in the 2.4GHz spectrum: Bluetooth, cordless phones, microwave (unless you cook a lot of Hot Pockets, this isn't likely to generate permanent issues), car alarms (hey...you never know!), some wireless video devices like range extenders...unlicensed spectrums are full of entertainment.
Of course, you have walls, furniture, etc. that can cause issues, too. It doesn't sound like that's your problem, but without a complete picture it's difficult for me say for certain.
However, I tried leaving it unplugged overnight to let it cool down. No dice there, a fail as soon as I turned it on.
I need to try a 5Ghz Wireless N capable device and see if that's a better bet.