Internet speed / reliability issues

Hey everyone, 

 

I recently started having some issues with my internet connectivity. Some moments it will be worked perfectly, getting my correct speed of 250mbps download, and 25mbps upload. Out of seemingly nowhere, it sometimes drops the speed anywhere from 0.9 Mbps - ~50 Mbps. (speeds checked with speedtest.net) When it drops to these speeds, it's typically not useable as it's not recognized by most of my devices. I've been told to look into my modem settings and see the channel frequencies and things however, I don't know what to look for. If it matters, I have a Netgear CM500 and the Google Mesh Wifi (the first edition, not the brand new model).

 

Thank you very much for any help you can offer! 

Have a wonderful day / night 🙂