My setup is used to connect two remote sites. One site has ZT running on an Edge Router Lite doing only routing between ZT and the local network (Site A). The other side has ZT on a VM running Debian 10 with the ZT interface in bridge mode and the interface which is IP’d is on a Fortigate Firewall (Site B).
On February 26th, everything was working properly and I could reach devices in site A from Site B. The next day, there was no connectivity between the two sites, but both sides showed a direct connection when doing a peer listing. Trying to troubleshoot, I found that on site B, a tcpdump on the ZT interface showed the Fortigate firewall sending out an arp request for ste B, but there are no replies. Likewise, on site A, it is sending out arp requests for site B, with no responses.
So far I have upgraded both sides to 1.6.4, was on the 12.4 release, and I have still having the same issue. I have checked under my network config, and the nothing has changed in the flow rules that I can tell.
Any thoughts on how to further troubleshoot this?