Purchased a Beryl MT1300, and have upgraded the firmware to 3.211.
Connected to my cable modem via the included ethernet cable.
When connecting to the MT1300 via 5ghz wifi, the connection will fail within 1 minute or less.
This pretty much eliminates the purpose I purchased the router for. Any fix on the way?
What power adapter are you using?
Use the one comes with the router.
I have one typeC power adapter and it causes the router crashes when connected to wifi.
It’s the stock adapter out of the box.
When using the router connected to my PC by ethernet and the router connected to WAN via 5ghz it seemed to work fine. Router connected to cable modem via ethernet and my PC connected to 5ghz was dropping constantly though.
I did a factory reset and it seems to have helped. Will report back after some more use.
Load LuCi and let the games begin 
at least its OpenWRT 19.07.08
Can you post the portions of the System Log and the Kernel Log before/after the disconnect event?