Keeps completely cutting out while saying it’s fine.

Every 1-3 hours my internet will completely cut out on all devices, while the xfinity app says it’s working as intended. Absolutely nothing will load and I don’t know what to do anymore. I’ve tried every troubleshooting method I could find online from power cycling to replacing the gateway and having a technician out and it is still happening. When it does work, I am getting 100mbps download and 1mbps upload on a 2gbps plan. It had worked completely fine from the 2nd to the 18th. I’m not sure what else I can do.