Using cat6 connected from PC to TM supplied Unifi TP-Link Router (Black with 3 antennas).

Just had a visit from TM technician and he tested with his own router and laptop with same results.
He called back to  home base and they have verified that the port is set to 800 Mbps.
He also tested the fiber signal strength and it was -15.47 dbm which is in the nominal range.

He said someone else will come back on Monday to solve the issue.

Ah... I think it is the original  patch cable that came with the unit on installation day. So you think that might be the solution? Swap a cat 6 patch between the o.n.u and the router?

The TM technician that came just now brought his own laptop, router and patch cables though I am not sure if they were cat6. I would assume that he would be using cat6 to test. He also could only get 200 Mbps on his own setup.

Damn have to wait till monday cos all the stores are closed. What a bummer.