Please install the latest driver from atheros-drivers.com for your specific chipsets. I would suggest not relying on Windows Update for the latest drivers. I believe the latest driver relevant to you would be version 10.0.0.341
I specifically meant an entirely different router or AP, not the Turris Omnia.
As iddqd mentioned, if you are in an urban area with many wireless networks nearby there may be interference caused by other devices on the same frequencies.
I’d encourage you to check out the below post, as I specifically did the tests to try to emulate your issue. Alas I do not have access to the exact configuration of your systems, but I think you will find it informative.
https://discourse.labs.nic.cz/t/wifi-radio-test/1056/1