FRR OSPF state stuck in Extart / Exchange because of MTU following pfSense restart
1. Build FRR with OSPF, build the VTi interfaces, etc. Start OSPF and it will work. OSFP will link up neighbor state "Full/DROther"
2. Reboot pFsense and OSPF will not move past neighbor Exstart.
3. Manually set the MTU to 1400 inside the "Interfaces / if name (ipsecxxxxx)" - OSPF works and survives a reboot and moves immediately to neighbor state "Full/DROther"
It seems the MTU on the VTi interface is somehow altering after a reboot.
Also, I couldn't get any other MTU to work, 1420, 1432, 1436, only 1400 worked.