Deactivate the DHCP server at the ISP router, then set up a static WAN IP address at the pfSense box, and let
only the DHCP server from the pfSense working, not vice versa, please! And the bridge port option should be
not used by you it often coming besides with other problems.
Route where you can and bridge only if you must.
I have a similar set up without any kind of problems reaching the devices in front of the pfSense and behind
of them and on top also both WebGui interfaces of the both routing units. The double NAT will only "eat"
3% - 5% of the entire throughput, pending on the power your hardware.
In my eyes your problem will be pointed to the both DHCP servers each in one network and the bridged port
nothing else.