I just read Sony recommends to turn off 108Mbit turbo-g mode on the access points but mine is running like that and have no problem - it works perfectly with my TH even when it's being used at the same time with other laptops in the same network.
Anyone had any problems after installing the wifi update?
I had some issues before the path (that according to the papers right out of the box the TH55 came in, shouldn't be applied to European TH55), but after installing it, everything runs smoothly.
Anyway I guess, as you say, Sony is just covering its back... just in case...
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Amstrad CPC -> Amiga -> PC -> TH55/E2 ^____^