In additions to the suggestions below, would actually go out to the garage and check the signal strength with WiFi Analyzer or similar. I added a separate router in the garage (ethernet backhaul) due to the signal loss issues.
Do you have the 2.4Ghz and 5Ghz band on separate names(SSID)? This is called band steering and can cause problems with some devices. Also, do you have any spaces in your SSID? Last, how is the signal strength in your garage?
Correct. Why else would you connect a garage door opener to a router? You'd either open/close it via the transmitter included with the opener or an app on a phone. Unless it also has cameras, there isn't much to check on a garage door opener.
I have an older Chamberlain setup that has a similar integration setup. Basically using the older setup you get a garage door remote that has an Ethernet port instead of a button to push. Plug it into the nearest Ethernet port within remote range of the garage door, setup the app, and it just works. I believe most newer openers have a wifi module built into the opener itself.
Strangely enough I found myself having to troubleshoot a problem with my setup and guess what feature doesn't come with a $1600 Unifi switch? 10Base-T backwards compatibility.