Firmware 188.8.131.52 does has a routing bug, are something that looks like it.
With LAN IP 10.30.0.0 with subnet mask 255.255.0.0 it will not respond to 10.30.2.x
It will only respond to 10.30.0.x
Routing table is ok. Firewall is ok, auto block list is empty.
Ethernet capture shows a ping arriving but the Yeastar does not respond.
If it can be solved it would be awesome.