But why it looks like to me only upload traffic is impacted. I could be totally wrong. Maybe someone with more knowledge can help to investigate this.
And completely out of sense the Speedtest gives bad upload results when the Laptop is in the same room as the router is and one can expect highest possible upload.
When I move it to my most distant room with lowest signal and it shows 100-150Mbps upload.
Actually before the above mentioned patch
net.netfilter.nf_conntrack_tcp_no_window_check=1
I couldn't open one particular website on my wired PC, but I could open it on the Laptop. Isn't it strange. I can't remember if I tested bufferbloat before the patch.
After applying the patch I can open the same site successfully wired and wireless.
Probably it's time to play with
ethtool -K br-lan tx-checksumming off tx-checksum-ip-generic off
once again.
Edit - Again back to the settings @anom3 pointed out
config ecm 'global'
option acceleration_engine 'auto'
config general
option enable_bridge_filtering '0'
option disable_offloads '1'
option disable_flow_control '1'
option disable_interrupt_moderation '1'
and
ethtool -K br-lan tx-checksumming off tx-checksum-ip-generic off
This time I don't want to hurry and say it is finally resolved but see the wireless results now
bufferbloat test works too. No more 30Mbps cap on upload via wireless.
And on my Smart Phone the latency and ping lowered by 10 times!
Check your settings guys and sorry if I pointed anyone out in the wrong direction in my previous posts.
Bonus - Bidirectional (the most difficult) iperf3 test wireless from Laptop.
Latest Update - As I have an OTT based TV Service which receives constantly data traffic between 5-30Mbps I could presume there was still an issue because the TV channels were interrupted for 2-3 seconds every few minutes. The interruptions itself were more frequent on 4K TV channels and it's logical because they use more data (around 25-30Mbps HEVC data flow). And that is something no-one would accept.
With all the latest changes described in the middle of this post I really no longer see TV Service interruptions.