In case anyone's having connectivity issues like I was, I thought I'd share what fixed it for me.
What was happening for me was that my download speed would grind to a halt, and I'd get a yellow exclamation mark on my signal strength indicator in the top right corner. I'm using an old TP-Link Archer C7 with OpenWrt.
I've seen people recommend disabling WiFi Power Management in developer tools, or changing 5Ghz channels on your router. Neither of those helped in my case. What fixed my issue was switching the 5Ghz channel width on my router from 80Mhz to 40Mhz. If changing channel width alone doesn't fix the issue for you, try experimenting with different combinations of channel and channel width.