@Riley_S I wish myQ had some tech support or forum.I can't find any way to reach them beside a chat.  Since they are on the other end of the handshake, it could give a quicker solution.  And I would think they could benefit.  I don't see anything special or unique or complicated about what I'm trying to do.   

  @Nstanton62 Did you try setting the RE315 as an Access Point (AP)?  Not as a OneMesh Extender?  The pairing software probably doesn't like the Virtual MAC address.

  @jzchen Thanks for the suggestion. Yes I did try it and the RE315 went offline from thh tether app and could not be reconnected.  I had to reset to factory defauls and re add it to my devices.  Apparently it needs ethernet wired feed to operate in access point mode?  I don't have ethernet where I want to locate it.

I am working with TP_Link support in paralle to this.  We found that by changing the 2.4G band to no security on the entire network (AX73 main router and RE315 as range extender copying settings), the myQ opener connected and operated successfuly like normal.  Apparently it is an issue with security communicating through the RE.  Awaiting further response from Support.  

  @Nstanton62 Just posting the conclusion for others that may have similar problems. 

TP Link Support was very responsive and through email we have been working together to troubleshoot and resolve.  They asked me to try removing security (no password) and see if the MyQ opener would then connect through the RE315.  I had to go back to the main router AX73 to do this, since the RE315 security is not settable but passed through from the main router when in RE mode. With no security protocol the MyQ opener connected throught he RE315 with no problem.

After that TP Link Support provided a beta firmware update for me to test.  They asked me to test it using various security protocols - WPA2/PSK, WPA/WPA2, WPA2/WPA3 and WPA3.  It worked in all cases. Note though that a second MyQ opener, which was connected directly to the main router AX73, did not work with WPA3.  A couple other devices were also not compatible. Support indicated a public firmware update will be issued at some point to include those changes. 

Edit: I should add that the final testing with beta firmware was with OneMesh and Smart Connect turned on, as I had hoped to be able operate the devices.