The log does not show anything special.
I am trying to replicate this problem in my side.

Here is a check list. Pls help to verify that you are using the same.

  1. AR300M with 3.212 firmware
  2. no openvpn, no wireguard
  3. no mac clone
  4. Just repeater to an open wifi network
  5. DNS rebind protection is turned off
  6. Client data statistics is turned off
  7. The web panel is not activated in your browser all the time. Turn it off when not use.

If the above all matches, can you please check if any of your clients may make trouble? You can disconnect one of them to see if things improve.