Cell Phone And Internet Questions

Two topics/questions in one post, if I may:

1. I'm having trouble with my Samsung Galaxy S21, through Verizon. I'll place a call, and it will go through quickly, but very shortly after connecting, the sound will totally disappear. No echo, no static, just dead silence. Then when I attempt to call back, it takes forever for the "connection" to be made, and the other person's phone to start ringing. Any hints, tips, or suggestions?

2. At least weekly, and often twice a week, I have to reset my router in order for my WiFi only tablets (my Android, and wife's iPad) to work. I get my service through Cox, and my modem/router combination is a Netgear Nighthawk unit with 4 (?)antennas(?) on the back of the piece. Once reset, things work fine until the next time the signal is interrupted. Is my problem likely the router? The signal from Cox? The coax cable running through my house? Something else?

Thank you for any suggestions you may be able to provide.