I have some strangeness going on with my new Deco X20 mesh system ... hoping someone from TP-Link can provide some guidance.

I have several devices in the home that are not reaching the speeds that the Deco claims to provide.
 

Here is my setup:

CenturyLink Fiber - 940/940 Rated Line Speed (Default CenturyLink router is C4000XG)

Higher End PFSense Hardware Firewall - Dedicated hardware. (4 x Intel NICs, 8GB of RAM, Pentium N3700 cpu, 128GB M.2 SSD)

Deco X20 3 Pack in AP mode.

2 Story Townhome - 1800 Square Feet. Drywall/Plywood between APs.

Probably 25 devices connected at any given moment. TVs, Thermostat, Cameras, Laptops, Phones etc.

No Ethernet Backhaul

Fast Roaming is Disabled

Congestion on both bands is average and doesn't impede connections to other routers.

Scenarios:

2020 Macbook Pro / Connects to default Centurylink Router wirelessly on 5ghz at 1167mbps with download speeds above 600mbps from major speed test sites.

After installing the Deco, the Macbook will not connect to any Deco AP on 5ghz at more than 866mpbs. Even when connected on 5ghz at 866mbps, download speeds hover around 250mbps from all the major speed test sites. When I connect the Macbook to the main Deco X20 via ethernet, my download speeds are at or very near my rated line speed of 940/940 This eliminates the PFSense box as a cause. When I hardwire into the PFSense box I also hit rated line speeds.

If I connect the Macbook via ethernet to one of the satellite Deco's, I get somewhere around 650mbps downloads.

I also have a Samsung Galaxy S21 Ultra that exhibits similar behavior. Connects to the Deco at no higher than 866 and downloads from major speed test sites at around 250-300mbps. Connects to CenturyLink router wireless at 1200mbps and download above 600mpbs from major speed test sites.

This is not an enormous space ... it doesn't matter where I place the APs or how near I am to the APs the Macbook and the S21 Ultra will not connect to Deco Aps at anything over 866mbps and download speeds are horrible. This is not an issue when removing the Decos from the configuration and strictly using the CenturyLink router wireless. The phone connects to the CenturyLink Router at 1200mbps and download speeds from major speed test sites are 650-750mpbs.

This is not a huge space ... I do not understand why these newer wifi6 capable devices, which connect to other routers at 1167, 1200 or 1300mbps without issue, cannot connect to the Deco system at more than 866mbps. And the download speeds when connected at 866mpbs are roughly a quarter of that speed.

Hoping you can provide some ideas.