Nighthawk Router RAX-35 Keeps Dropping Internet Connection

My router keeps dropping internet connection.  Once I turn it off and turn it back on, it comes up.  Stays up for maybe a day or two and then I have to turn off and turn back on again to reconnect.  It is a NIGHTHAWK AX4 4-stream wifi 6 router Model RAX35.  I use Microsoft Edge on my desktop computer.  Firmware version is V1.0.3.80.  It is located in the livingroom of my 1270 sq ft home.  We only have 21 devices in the home.  It is also connected to a Mikrotik RouterBOARD and Cisco ATA with Router SPA122.  Cable provider, which is Greenlight Broadband, added these other routers.  They added this because we have a printer with analog fax and stated that since broadband is fiber optic, we needed these other routers.  We never had this problem with our other Netgear N750 Wireless Dual Band Gigabit Router.  What do we need to do from here?  Hope there is something we can do.  We are not gamers.  Basically use internet for streaming services, online banking, social media and such.