@Kevin_Z Nat boost deactivated and it works fine for months now. Is the beta firmware gonna solve the issue so that i may enable NAT Boost again? Because with NB off i have speed loss of about 30%....

Well maybe the above mentioned error by your count does nothing, by my count it restarts router 1-2 even 3 times a day, not ok at all. My TP Link is Archer C9 V5.0 ,firmware version 1.2.4 build...