Netgear R7800 exploration (IPQ8065, QCA9984)

I recently bought TP-Link C2600 with IPQ8064.
I wanted to use it with my 250/20 Mb/s connection with SQM, yet for some reason this router can't properly utilise this connection. I've seen reports in this thread from other users saying something similar.

I also came across this post: Best Wireless AC router for LEDE?
If it's true then I'm hugely disappointed.

Users in this thread also indicated problems with SQM:
Post 386
Post 422

Can anyone advice me what should I do? I bought it from Amazon so I have 30 days to return it.