Right, I have managed to sort this out after a few hours of trying, hopefully this will help others having the same problem.

- I tried logging onto the 5350 via WiFi from my android mobile phone. This worked fine and I could access the configuraiton page (192.168.0.1 password:admin) with no problem. I then went to the wireless setting page and changed the mode to 11g only. I then logged in again from my windows 8 Dell laptop and I could access the configuration page without a problem and no timeout!

So, I don't know if this is a Windows 8 / Dell / Broadcom problem, or if it is a problem with the M5350, but whatever, WiFi 11g is fast enough for me since the bottleneck will be in the 3G connection.

Now this is sorted the M5350 seems to work very nicely. Just a small point, I have set the pin code security to 'enabled' for my SIM. This means that if i lose the 5350 no one can use my data connection. It does mean that each time i connect i must type in the PIN code using the config page / advanced settings (192.168.0.1) but I think this is worthwhile.

Many thanks,
Tom