Internet disconnecting every couple of hours for a few minutes

There's no specific pattern, the connection just disconnects for some minutes every two hours or so. It happens on every device; the modem is still on, it's just not connected to the internet. The same happens for wireless and wired devices. I tried contacting my ISP but they are pretty useless and their answer was "idk maybe you have a virus?". I tried changing the channel on my modem's settings so maybe that'll work; I just did that, so I'll find out later. One thing I noticed is that, in my modem's settings, where I can do Ping tests, the pings to "DNS Server 1" always fail; other pings work. Could this be something causing my problems?

Well it could be a virus, for safety check all your recent installs. Otherwise try to ping test your IP address (usually 192.168.1.1)

You can do a ping test by opening the command prompt and typing "ping 192.168.1.1". If you are not sure what your IP address is, type "ipconfig /all" and check the one next to 'Default Getaway'.

If all fails, type your IP address in a browser. And navigate and try to reset all settings to factory state. Then contact your ISP once more to set it up from scratch (or set it up yourself if you are aware of the username and password)