So after doing much searching and ending up with most threads ending in the same way, (no further response from TP-Link) I decided I had better try to get the problem I'm having solved.  I have the X20 3 pack, and all are current firmware. I'm not getting anywhere the wifi speed I should be.. I'm talking like 9-12 kbps per device. Sometimes it will jump up to 2 or 12 Mbps but then it drops down again and then will also disconnect lots. ....
This is nowhere near the 1GB i'm paying for. I've checked without the Deco and my internet is working just fine, even the wifi from my router.  This is only when accessing wifi through the x20 units. .  If I plug an ethernet cable into any of the Deco units, I get no slowdown. but on wifi, it's brutal. The main page in the app says everything looks good! But it obviously isn't.  Any help resolving this would be appreciated!