lost WIfi on NightHawk M1

hello
I'm writing to you for 2 problems with 2 NightHawk M1(firmware version NTG9X50C_12.06.12.00 (with 2 different operators) :
- when I connect to the Nighthawk's wifi after a while the SSID name disappears from the wifi network list of my laptop and I lose the connection (I have to press the power button once like I did when I woke up and it works again) (?)
- when I want to use the router via the ethernet cable I don't get a connection (no ip address), as if the two of them couldn't communicate.

thank you for your help