Routing to another gateway

[robepate]

Hello ,  I have a network with two gateways, the default is the opnsense firewall (for internet access) and the second is a router that connects a secondary site in vpn.
I configured a static route for the remote network and by running pings test everything seems to work.. but works only pings other traffic network to remote site as RDP or VNC not works !!!
I think I have solved it using the "Bypass Firewall Rules for Traffic on Same Interface" function.. but why ??
why does ping work without it?

Thank you

[daigoro]

Asymmetric routing (https://en.wikipedia.org/wiki/Talk%3ARouting#Symmetric_and_Asymmetric_Routing).
Ping (ICMP) can handle it, all other protocols not.

[robepate]

Thank you