Thank you for your feedback.
It is really interesting our router has a same firmware. I’ve made 2x3days recording with no issues.
I know you already spent way too much time on this issue, but if you still have a possibility to test something that would be helpful for us at least to know where to search the issue. Could you please try is that issue present as well when the wifi disabled on the router? There’s a switch on the back, need to push and hold down for 5 seconds for disable the wifi.
Or update the router to the current firmware release: https://www.tp-link.com/us/download/TL-WR841N_V11.html#Firmware