Just setting up the deco m9 plus.  I have fiber, so no modem, just the Ethernet jack.  Main unit sets up and seems to work ok, even though some devices get the incorrect password about 50% of the time.  The main problem is once I get the second deco setup and then move it about 20ft away it isn't found again on the app and all I get is the flashing red light.  If I move it back to right next to the main unit then it's green on top again.  The range can't be that bad on these can it?

This happened after I finally got it connected after multiple resets and about 2 hours online chat with tplink.