Configuration: set net.link.ether.inet.maxhold(number of packets to hold per ARP entry) to 5.

Since maxhold's default value is 1, it may not be enough for some
applicatins, so increase it to the value of
net.link.ether.inet.maxtries(ARP resolution attempts before returning
error).

config.ini

@@ -69,6 +69,8 @@ net.inet.tcp.tcbhashsize=65536
 kern.ipc.somaxconn=32768
 kern.ipc.maxsockbuf=16777216
 
+net.link.ether.inet.maxhold=5
+
 net.inet.tcp.fast_finwait2_recycle=1
 net.inet.tcp.sendspace=16384
 net.inet.tcp.recvspace=8192