I have some interesting observations to share and would appreciate any feedback. To summarize, I have an iPhone5 and an iPad Mini. I upgraded both to iOS7. The iPhone works fine. The iPad Mini is unable to connect to some routers that previously (with iOS 6.x) were not a problem. I get an "unable to join" error. This includes my home router (very frustrating). I have tried every suggestion I could find on this thread and elsewhere. (Forget network, airplane mode-->reset network settings, reset router, remove router password, change router SSID, reset all iPad settings, etc.) Again, these are routers that the iPad previously connected to with no problems.
Here's the interesting part. I just upgraded to iOS 7.0.3. Even though the list of bug fixes did not include wifi connection problems, I was hopeful. Upon rebooting, I now couldn't even see my router on the list of available networks. Previously, I could see it, just couldn't connect to it. Strange. I tried switching WiFi on/off, airplane mode on/off, rebooting, nothing. My home network was not detectable. I was about 30 feet from the router. I then moved to about 1 foot from the router and it appeared. Furthermore, I could now connect to it for the first time since the move to iOS 7. I thought "hurray" problem solved. But not so fast. When I returned to my bedroom 30 ft away, I was still connected to the router but no internet. Speedtest: "network connection problems." If I moved back to 1ft from the router, super fast connection. I checked speedtests and latency measurements at 1ft, 10ft, 20ft, and experienced a dramatic drop in speed and increase latency as I moved away from the router. At 25ft, I lost all internet traffic although it showed I was still connected to the router with a strong signal. If I disconnect from the network, I could see the router at 30ft again, but when I try to reconnect, I am back to the "unable to join network" error. But I can join it just fine if I'm 1ft away.
Can others try this? If you're unable to join the network, what happens when you move the device right next to the router?
I welcome any thoughts about this, and any suggestions.