Hi,
Please check the routes on the pfsense to the 172.16.30.0/26 subnet. If no routes to the subnet then try adding one static route to the 172.16.30.0/26 via default gateway 172.16.25.4.
When you set default gateway as 172.16.25.4 the pfsend sends all the packets to the 172.16.25.4 however when you change the default gateway to 121.122.121.122 then pfsense would be sending all the packets to the your public gateway. To handle you internal LAN2 network you need to add static route on the pfsense.
Thanks,
Vikas