There are two hosts direct connected via cxl0. The problem is visible when
pinging (1) between jails on the same host and (2) from an affected jail on
host 1 to host 2. On an unaffected host both of these operations succeed.
Using tcpdump on the physical (cxl) and virtual (cxlv) interfaces shows the ARP
requests and responses, but in an affected jail the ARP tables aren't updated.