Intermittently slow internet

A day or two ago the wifi speed on my PBP was fine; now it’s slowed to a crawl. My phone can connect to the wifi and get normal speed, suggesting the problem is with the laptop. I can also use a wired connection between the phone and the laptop to get fairly good speed using the phone’s wifi connection.

This happened before several months ago, and I don’t remember what fixed it. I’ve installed all the updates that show up automatically in pamac. I’ve looked through several other threads on similar problems, but don’t see anything that clearly looks like a solution to my problem. My knowledge of Linux is around beginner-level.

Any ideas?