IPhone 5 / iOS 6.0.1 - no internet access over Wi-Fi (at work)

Question

Hello,
we have a customer whose employees have upgraded about 80-90 iPhone 3GS/4/4S to iPhone 5 (or, mostly 5s, some have upgraded their 3GS to 4S).
Among all these phones running iOS 6.0.1, so far 3 users are reporting problems connecting to the internet over the company Wi-Fi network.
There's no problem at all connecting to the Wi-Fi network and they all have good signal strength, they get an IP from the DHCP server on the company LAN, and they can even connect to a local web server on that same subnet.
It is impossible to connect to any service outside the company LAN, even knowing the IP of a web server on the internet, thus excluding DNS problems.
Users have found their own way around this problem by restarting their iPhones, which solves the problem for the rest of the day (at work), and also just turning off Wi-Fi, using cellular data, helps them through the day...
After a restart, they can leave the company network during lunch hour, using cell data, and when returning to the company Wi-Fi it still works fine.
But the next day when these users come back to work, after having been connected to their home Wi-Fi network, the problem returns. No route to internet. A restart of the phone or  resetting the phone's network settings resolves the issue until the next day.
I bought a system status app which shows me the iPhone's routing table and its connections, and when the phone is having these problems, the routing table shows that the primary default network interface is en0, and the primary default gateway is the company network's router.
At least one of these 3 users has a 5th generation Apple Airport Extreme at home, using its default wireless settings.
The company's using only Apple Airport basestations for their Wi-Fi network, WPA2, 2,4 and 5GHz.
I might add:
- no other phones/devices are having issues with this company's Wi-Fi network.
- this issue may apply to either iPhone 5 or iOS 6.0.1, and may be present even on  4S phones, but the users haven't yet reported it
Anyone else having this issue? Any clues except waiting for iOS 6.0.2?

Answer 1

Here's what ahs wored for me int he past:
1) Turn the Phone off, then back on
if not that, then 2) Hard reset the phone (Hold power and home for 5 seconds)
if not that, then 3) turn the phone off, then use a cotton swab with some alcohol to clean out the dock connector or the headphone jack
if not that, then 4) Play a song. With no sound coming out, reconnect it to a speaker dock, then disconnect it again. Sometimes the last time it disconnected didn't register.
if not that, then 5) Rapidly plug and unplug the headphones about 5 times - this may unstick the headphone jack
if not that, then 6) If you get sound through headphones, plug in headphones. Start a song. Unplug the headphones
Hopefully one of those works