Home wi-fi network will periodically crash when MBP is connected to wi-fi; everything is fine on ethernet

I have a 2018 MBP that's connected to an Ethernet cable 99% of the time. This is my work machine, and I'm on it all the time. However, whenever I disconnect my MBP from Ethernet, and allow it to connect to WiFi, my entire home WiFi network will periodically disconnect.

Approximately every 15 minutes (it's actually almost exactly on the 15 minute mark), my home WiFi will lose its Internet connection. Looking at my WiFi diagnostics, it complains about DNS connectivity being an issue. I can restore the WiFi router's Internet connectivity by changing the DNS server in the router, but then 15 minutes later, it's down again.

Is there some kind of DNS server that could be running on my MBP interfering with my local network DNS? How would I even go about checking for that? Could there be some other kind of phenomenon going on?!

Edit: I'm using an AmpliFi Router HD mesh WiFi router with 1 base and 2 extenders. Firmware version 3.3.0.

I resolve this every 15 minutes by cycling back and forth between 1.1.1.1 and 8.8.8.8 as the DNS servers on my router.

Here's a screenshot of the error that I'm seeing from the router:

Also, here's my arp -a output, in case it helps

? (169.254.80.182) at f0:9f:c2:36:50:b6 on en0 [Ethernet]
? (169.254.85.113) at f0:9f:c2:36:55:71 on en0 [Ethernet]
amplifi.lan (192.168.134.1) at f2:9f:c2:36:1e:49 on en0 ifscope [ethernet]
philips-hue.lan (192.168.134.2) at 0:17:88:4f:4f:43 on en0 ifscope [ethernet]
home-mac.lan (192.168.134.5) at 78:7b:8a:c0:19:40 on en0 ifscope [ethernet]
wills-iphone.lan (192.168.134.218) at 40:4d:7f:95:e7:cf on en0 ifscope [ethernet]
? (224.0.0.251) at 1:0:5e:0:0:fb on en0 ifscope permanent [ethernet]
? (230.230.230.230) at 1:0:5e:66:e6:e6 on en0 ifscope permanent [ethernet]
? (239.255.255.250) at 1:0:5e:7f:ff:fa on en0 ifscope permanent [ethernet]

I've never used the AmpliFi system personally, however it does seem to be unreliable especially when compared to the UniFi product range. There seem to be a lot of people who've tried AmpliFi, had problems, then switched to UniFi and been very happy.

Also personally having used UniFi at four separate installations over several years I have never encountered any problems of any kind at all. UniFi just works perfectly and forever.

It does take a bit more effort to setup, but not that much. Certainly easier than troubleshooting the issue you're experiencing now, and it should then operate for the next decade without being touched.

UniFi uses a wired backhaul instead of a wireless one which frees up radio spectrum and reduces latency. It's also cheaper. Yay.

Without knowing the size or layout of your house, it's difficult to recommend which UniFi products you should go for. Generally though the short range ones are better if you're going with a "mesh" setup. In fact it's often recommended to configure them to operate at the lowest possible power level to prevent devices connecting to the wrong hotspot.

For about half of the installations I've done though, a single access point has been more than enough, so I'd start with just one.

UniFi lacks advanced features such as firewalls/etc. If you need that, get an EdgeRouter X. If you don't need it, you should be able to just plug the UniFi AP's into your cable modem.