Ok, here's the scenario.
The important thing to remember is that all was working well, as happy as 'larry the lamb'. Being that I was running Snow Leopard on my MacBook Pro 8,3 while accessing the internet through my iPhone 4 using it's Personal Hotspot feature (with iOS 4.2.5/4.2.6 running on the iPhone 4). Internet thethering worked beautifully between the MacBook Pro & iPhone4 and all was well. Some time before this I had used the Time Capsule's WiFi for internet access with NO problems (when I had dedicated broadband), but then switched to using mobile tethering (personal hotspot feature).
I then upgraded to OS X Lion 10.7 (11A511) the day it was released and did this over a friends fast internet connection using cable ethernet connection for quicker speed. While I was doing this, I also downloaded the latest iOS update for my iPhone 4 being iOS 4.3.4 (8K2).
Then the problems started.. I have not been able to connect to the iPhone's Personal Hotspot, nor the Time Capsule's WiFi and neither the Airport Express unit (that plugs straight into the power socket). All three devices say 'connection timeout'. Resetting them either physically (reset button) or through the Airport Utility using an ethernet link (in the case of time capsule and airport express) make no difference.
I wish I never updated the iPhone iOS and previously put of updating it for the previous few updates because the tethering worked so well on it, therefore I would want to downgrade it to iOS 4.2.5/4.2.6 again (need to locate and re-download those two versions and accuire instructions - if anyone could help, would be very appreciated?).
Now this is the strange thing:- Although I cannot connect to the Apple Time Capsule, Apple Airport Express and iPhone Personal Hotspot (getting the 'connection timeout' error all the time), I am however able to connect to a non-Apple device Vodaphone 3G WiFi point. The Vodaphone 3G device is a 3G USB mobile dongle that is plugged into it's own dedicated small WiFi base station.
I am at a loss as to what is going on here?