Having an issue with TM3402 modem

For the past week Ive been losing an internet connection approximately once a dat. To be more specific, everything seems fine on the modem side of things - all lights are illuminated etc but my router tells me there’s no internet. I called customer support who said everything was fine on their end. 

My solution seemed to be to reset the modem and reset the router (Orbi RBR50) to factory. This would work for 24 hours. So I decided the router wasn’t working and went out and got an Eero Pro (2nd gen). After a few attempts it got up and running well. 

This morning I woke up to the same problem. I tried connecting a laptop directly to the modem and it too was unable to achieve a connection.

Instead of resetting the router to factory I did a refresh followed by a few hard resets of the modem. Eventually it started up correctly. 

ive seen a few people with similar issues but have not seen a real solution. The ones with this problem seem to have the same modem as me (Arris TM3402). 

Anyone have a way to fix this? TIA