Terrible connection a short distance from the router

[wireless]

I am on a 150 mbps plan with the Actiontec T3200M router. Despite the plan being 150 mbps, however, this speed isn't nearly achieved on any device in the household, no matter the proximity to the router. Of all devices connected, my personal computer a mere 10 meters and a wall away from the router is suffering the most. The computer reaches a 30d/10u bandwidth on 2.4G with terrible ping that varies from moment to moment. 5G fares even worse, with the computer outright refusing to use it and automatically switching back to 2.4G. The ping here is my biggest complaint; the effects of lower throughput is negligible for my usage, but the ping, which is anywhere from 5-50 at least and goes up to 1000 at most, renders even messaging on the computer extremely slow and inconsistent.

For comparison, on a previous Shaw network under similar circumstances, the computer would achieve 175d/20u on a 150/15 mbps plan.

Here are my current 5G settings:

https://bhzof35755.i.lithium.com/t5/image/serverpage/image-id/8440i7062EF2C46FAF60C/image-size/large?v=1.0&px=999

Tips on troubleshooting these issues would be appreciated.


More... (https://forum.telus.com/t5/Internet-TV-Home-Phone/Terrible-connection-a-short-distance-from-the-router/m-p/93879#M20208)