Who still uses D-link 850L for turbo 800Mbps?
I think mine is bottle-necking and can only get max 300Mbps when direct download. Using cable of course.

Latest firmware 2.10TM.
Wifi, firewall, qos, and ipv6 are all turned off.
Direct download tested using IDM fetching from centos mirror, microsoft iso, and google drive.

The weird thing is, running speedtest is consistent at 840-850Mbps.
Torrent speed is also good at 600-700Mbps.

I tried plugging laptop directly to the ONU hg8240w and connect using windows pppoe. Yeah no problem getting full speed for direct download.
So definitely something is wrong with the 850L.

I'm confused why speedtest and torrents are fine, but normal http download was bottle-necked 

Am using AX on 1st floor (2.8ksqf) with unifi 100mbps. Test below are 30m away fro router with expressvpn connected. Bandwidth also changed to ensure minimal interference with neighbours

AX20 will the best choice. Or you can get AX73 if you wish to increase the budget.
Get during 5.5 offers.

Am using AX20 and speedtest done using Huawei P10 Plus old phone at dining area at lower floor