Repeated temporary outages on home network

I have an issue where my home network, including wifi and Ethernet connection, will disconnect from the internet for 5-30 minutes then reconnect. This may happen multiple times a day for a period of time, then not again for a few days or weeks which makes it difficult for both myself and Xfinity to troubleshoot.

I suspected it could be the wind physically blowing on the coax splitter which is is outside. Xfinity actually sent a tech and they tightened those connections but it is now happening again a few days later. Sometimes normal modem restart works temporarily, other times it does not.

I'm not losing power, I don't know what is causing the system to go down and restart multiple times a day on random days.