I recently installed a new RE315 extender on an AXE5400 router.  I also found like others clients on my network with a name of ANONYMOUS in the Tether app.  I found that these were legit devices on my network that did have names.  The propoer names did display when these devices connected to the router rather than the extender.  There seems to be a bug either in the extenders or the Tether app that is preventing them from identifying the proper name.  Has anyone found a fix for this?

Other odd names that I found and identified which may help others:

     Amazon -- Amazon Echos

     CyberTAN --  Hisense smart tv