Check the output when the issue happens:
ip address show; ip route show table all; ip rule show
ip route get 1.1.1.1; mtr -n -w 1.1.1.1
Check the output when the issue happens:
ip address show; ip route show table all; ip rule show
ip route get 1.1.1.1; mtr -n -w 1.1.1.1