uplink currently operates at a lower speed 100 Mbps

Hi I've just purchased 2 NWA50AX to vastly improve the wifi in my home/office
- I also purchased an additional 8port POE switch (TL-SG1008p)

I setup the 1st AP, connecting to the above with a new Cat6 cable.  It installed fine, and updated.  But then a warning was shown in Nebula:

"uplink currently operates at a lower speed 100 Mbps"

So far I have done the following
1. Tested by swapping with different patch cable
2. Tested by rebooting switch/AP with just AP connected

Both gave same results

I then Installed my second NWA50AX to the same switch and did the updates.  That switch also gave the same error.  I even tried it with the power cable to see if that was the issue - it wasn't. 

I then moved the 2nd AP to my Office/Den in a remote part of the house - and connected it.  It came up working fine 1st time.  

I reads to me that the TP Link switch is the prime-suspect?  Any further comment or advice?

Best Regards,
Jon