Why is one PC’s WiFi so much worse than the other’s?

Start by comparing the signal and link details on both PCs, not just the WiFi generation. Adapter model, antenna placement, and the band each one is using can all matter. If the weaker PC is on 5 GHz, try 2.4 GHz as a test. It may reach through the wall better, though it can also be slower or more congested, so judge it by latency and stability as well as download speed.

Check the antennas on the problem PC first. Make sure they’re attached properly and positioned clear of the case, wall, and nearby cables or metal. Desktop antennas can perform very differently depending on where they sit. Then update or reinstall the WiFi adapter driver from the computer or adapter maker, and compare the connection again.

Run a simple comparison before changing a bunch of settings. Put both computers in the same spot, test each one separately, and note the WiFi band, signal strength, and latency. If the bad result follows one computer, suspect its adapter, antenna, driver, or settings. If both struggle in that location, coverage or interference is more likely. A download speed test alone won’t explain huge ping spikes.

If gaming stability is the main issue, Ethernet is the cleanest test and often the best fix. Even a temporary cable run can show whether WiFi is causing the spikes. If a cable isn’t practical, a mesh node or access point placed nearer the computers may help, but test its placement rather than assuming any location will improve things.