Working on a client build.
Site X has a Fortigate cluster, and uses 10.150.54.0/24 split into /25 for corp wired and wireless.
Site Y has a Fortigate cluster as well, and has a 10.10.120.0/24 network and other networks. The Fortigate interface is 10.10.120.10. The 10.10.120.1 is an old MPLS circuit that will soon be retired (within the next few months).
Traffic from Site X to Site Y works for other networks besides 10.10.120.0. When I try and reach a server 10.10.120.5 - it fails. In checking into it, the server and some other older gear has a gateway of 10.10.120.1 (the MPLS), and the MPLS has no route for 10.150.54.0 so the traffic drops.
I have temporarily worked around it by putting a persistent route on the server redirecting 10.150.54.0/24 through 10.10.100.10 and that resolved it.
I hate using these sorts of 'kludges' when I'm pretty sure there's another easier way I could have done this through the Fortigates.
Both sites are on 6.0.11 if that makes any difference.