+1; TCP Reno will send by default one ACK packet for every two full MSS packets received, so for an MTU around 1500, that end up with a data stream to ACK ratio of ~ 40/1, your 800/18 = 44.4/1 is already too extreme to allow a hypothetical TCP Reno to achieve the full download rate your ISP promises... (In all likelihood your ISP uses some sort of ACK-filtering in your modem to "thin out" the ACK stream, which works bebause ACKs are accumulative and the receiver does not insist on receiving each individual ACK packet, as long as the ACK-sequence number gets increased). Modern techniques like generic receive offload (GRO) and generic segmentation offload (GSO) will merge mergeable packets into larger metapackets and will only ACK these meta packets, reducing the ACK rate.
Mmh, try to figure out the IP address of Valorant's Game Servers and run pingplotter against these...
Could you please post the output of (for 2, 3, 4 log into your router via ssh or putty, and run the commands on the command prompt offered by your router and then copy and paste the result into this thread, preferable as code:
Please use the "Preformatted text </>" button for logs, scripts, configs and general console output.
Please edit your post accordingly. Thank you! 
):
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A speedtest with SQM disabled
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cat /etc/config/sqm -
ifstatus wan -
tc -s qdisc -
a speedtest with SQM enabled
For speedtests, around here we like either the dslreports speedtest (see here for recommendations) or the waveform bufferbloat test (copy and paste the link from the Share your result field into this thread).