I’ve recently switched from DD-WRT to OpenWRT and expiermenting with various network configs I had under DD-WRT. One interesting difference with the OpenVPN client setup with an always on VPN type setup that uses redirect-gateway, all traffic including the router itself goes through the VPN on OpenWRT. Compared to DD-WRT which actually tells you not to put the router itself e.g. 192.168.1.1 in any VPN PBR policy, otherwise it causes lots of problems and ends in fail.
This initially confused me, because in the case of OpenWRT you need to then add static routes to force certain traffic over the WAN because of the router itself being routed to the VPN. Compared to DD-WRT which routes clients through the VPN but doesn’t make the router itself go through the VPN so you didn’t need to do it.
Why the difference between the two firmware? Is it a case of both firmwares doing routing differently?