I am using the latest release firmware for the Deco X60 and have discovered what looks to be a firmware issue.  When doing a speed test from the router using the tplink app I would consistently get around 950Mb up/down (as expeted with the 1Gb service I have).  When performing a speed test on my devices, however, I would see around 100Mb down and around 11Mb up (or much worse).  I also have had other networking issues which I couldn't explain.  After doing some debug I found the root cause of the issue to be enabling the prioritization of my Ooma phone from within the Tplink app.  That was the one and only device I had prioritized.  Once I disabled prioritizing my Ooma device I was able to get over 700Mb up/down with the speed test from my laptop.  Similarly, my other devices confirmed the improvement.

The odd thing with this is I have a second location with the X60 and a Ooma device that is prioritized and don't see this issue.  The ooma device on for this network is many years old while the location with the issue has a new Ooma.  There may be other variables at play here (e.g. location without the issue uses PPoE and VLAN tagging while the other does not), but I wanted to pass this info along.

This is informational for your engineering team to be aware and perhaps for anyone else out there who may be experiencing similar issues.  I figure this is likely an edge case as it clearly wasn't a problem for similar setups at 2 different locations (although not the same configuration as I've explained above).