I am running Andiodine under Android 13 (AOSP) and experience a total block of traffic when the option "activate standard route" is chosen (without that option I can ping the remote server at, in my case, tunnel IP 10.0.0.1). The reason seems to be that no exception is made for the traffic to the remote name server. A root shell reveals that all traffic seems routed through a table "tun0", on which only the tunnel interface is listed:

ip route show table tun0 gives:

default dev tun0 proto static scope link
10.0.0.0/27 dev tun0 proto static scope link

Also, for the name server 192.168.1.1, through which the DNS requests are routed, the default route is mistakenly set to table tun0:

ip route get 192.168.1.1 gives:

192.168.1.1 dev tun0 table tun0 src 10.0.0.2 uid 0