Welcome snookerfan.
Mostly, a/c do not have wi-fi operating onboard, so just turn the wireless off BEFORE you switch off the PC BEFORE entering the aircraft. When you switch it on (in the cruise) the wireless will not even try to start.
The On and OFF time for PCs is always clearly given. If you are not sure where to find the software switch for the wireless, just hunt through the main menu, or ask your tech support (if relevant). Failing that, the supplier or find the user manual online. Some laptops have a hardware switch for the radio, as well as a software switch, either way, the screen will tell you when the wireless is off. Then use as normal.