Fiber internet drops out when switching channels ?

I have had 1 gig fiber for over a year with a different company without any issues at all and a stable connection. Since I have moved and now have att fiber I have had nothing but issues. First of all the connection to devices were extremely slow for 1 gig plan so I called tech support , the reccoommended alll the basic reccomendations , which nothing worked. I called again becasue the problem persisted and we’re still no help so I asked to upgrade to 2gig. A tech came out to upgrade to the 2 gig and said that the gateway I was sent was the incorrect one for the fiber connection that was on the wall of the apt so it was not hooked up correctly. It is now upgraded to the 2 gig and I have still having issues with the connection dropping out. Each device is working better now the set up is correct , but I believe when the channel switches over that’s causing a brief drop out. Is there any way to check to see if that is the case? I need stable internet for work and gaming. The tech support lines have offered no usable help. I had this same issue with spectrums new routers also but once I switched my own router the issue was fixed since it didn’t have that drop out.