I have upgraded to TM Unifi Turbo 800Mbps for quite some time but yet to realise the speed promised by ISP. In my case, it is not fair to blame the ISP because the bottleneck was not at their end, rather due to my router. When OpenWRT announced the release of version 19.07, I took it for a spin and enabled the new flow offloading feature. The performance increase was significant.
Having flashed my TP-Link Archer C7 v2 with OpenWRT, I understood that I was giving up the NAT boost feature that came with the stock router. It was an acceptable trade-off given that I was then using internet speed of 100Mbps and lower previously. After upgrading to TM Unifi Turbo 800Mbps, speed tests revealed that my router could only achieve slightly below 300Mbps until I upgraded to OpenWRT 19.07 and enabled flow offloading feature.
I performed sysupgrade from 18.06.5 to 19.07 then enabled flow offloading by going to
Network > Firewall and you should then see the Routing/NAT Offloading under General Settings. Screenshot below:
I enabled software flow offloading. As this feature is not compatible with SQM, I had to remove the SQM package. Hardware flow offloading is not available for Archer C7 v2.
With flow offloading enabled, the download speed reached 719Mbps. No doubt this is still a bit of a distance from the 800Mbps speed offered by my ISP though still an appreciable improvement.