MR70-MS70 one satellite unit will no longer connect

[lgrekstas]

Mesh has one base unit (MR70) and 2 satellite units (MS70).  One satellite unit connects successfully but second unit will not connect.  System was working fine, until suddenly second unit no longer connects/syncs to base unit.  I direct connected second satellite unit via ethernet and units seemed to sync up, but as soon as units went into wireless mode the satellite unit lost connectivity even though it was set directly near the base unit.  

Does this mean the unit is bad and I need to replace the mesh system?

[FURRYe38]

Does the one MS connect wirelessly with the other MS turned OFF? 

What Firmware version is currently loaded?
What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too?

What is the size of your home? Sq Ft?
What is the distance between the router 📡 and satellite(s)🛰️? 30 feet or more is recommended in between RBR 📡 and RBS 🛰️ to begin with depending upon building materials when wired or wirelessly connected.
https://kb.netgear.com/000061709/Where-should-I-place-the-Mesh-WiFi-satellite-of-my-Nighthawk-Mesh-W... 📡 ‌‌🛰️

What channel configurations are currently set on the router?  

Has a factory reset and setup from scratch been performed since last FW update?