Few "generic" WIFI things I would check.
What "Band Width" is your Router Set to?
Often it is set to "Auto" or Widest setting, but that can also be the most unstable and often unachievable.
Like on 2.4Ghz you may have a Choice of 20,40,or 20/40.
20 will be the slowest but the most robust.
Sometimes it may be labeled as throughput (like 600mbps vs 300mbps). Try lowering it.
What happens on Auto is it tries to run on the highest through put, gets to many errors and falls back. Then thinks it can run faster and tries the higher bandwidth again.
Likewise most routers default the SSID for 2.4Ghz and 5.0Ghz to be the same name. And the device figures out what is best.
This can cause it to bounce between both. For that reason I always separate them and set each device to connect on one or the other. 2.4Ghz has more reach than 5.0Ghz does. So I typically only put devices that can really use 5.0Ghz on 5.0Ghz. Like why bother putting a Thermostat on 5.0Ghz.
Another Automatic one, is which channel. I scan for the quietest Channel with my phone (many apps for that) and set my router fixed on that Channel (more critical on congested 2.4Ghz).
It could be the 218 bouncing, but it has buffered enough music to ride through the bounce and still getting enough throughput.
Example of iPad user having the issue