Welcome to the Community!
I've searched for your account using your Community details and was able to find a match.
I've just completed a remote test and the results does not show a physical fault on the line outside.
Considering the test results, we need to eliminate any possible equipment, Wi-Fi limitation and bandwidth sharing issue.
Are your devices connected to the modem via Wireless?
If yes, please try to connect one of your devices via Ethernet cable to the modem and then monitor the connection.
If the connection is stable on a wired connection, I would recommend to check this article on our Community on Easy Steps to Improve Wi-Fi Connection In Your Home.
Should you need further assistance, please let us know.