An update…
Opened a ticket with Netgate but do not expect any updates from them now until Tuesday.
I have discovered that I can ssh into device (via VPN) and issue a ifconfig down / up on the LAN interface and connectivity is restored. So to keep this thing working until I can get on site or Netgate finds an issue I have added a crontab entry to run the ifconfig command every 5 minutes.
I also checked netstat when connectivity is down and here is the output:
[2.4.2-RELEASE][admin@shelter.applegate.privatedns.org]/root: netstat -i|grep cpsw1
Name Mtu Network Address Ipkts Ierrs Idrop Opkts Oerrs Coll
cpsw1 1500 <link#2>7c:38:66:26:ba:30 6412951 0 0 5694350 0 0
cpsw1 - fe80::%cpsw1/ fe80::7e38:66ff:f 0 - - 1 - -
cpsw1 - 192.168.1.0/2 shelter 5536 - - 2488 - -
[2.4.2-RELEASE][admin@shelter.applegate.privatedns.org]/root: netstat -i | grep cpsw1
Name Mtu Network Address Ipkts Ierrs Idrop Opkts Oerrs Coll
cpsw1 1500 <link#2>7c:38:66:26:ba:30 6412963 0 0 5694356 0 0
cpsw1 - fe80::%cpsw1/ fe80::7e38:66ff:f 0 - - 1 - -
cpsw1 - 192.168.1.0/2 shelter 5542 - - 2488 - -
[2.4.2-RELEASE][admin@shelter.applegate.privatedns.org]/root: netstat -i | grep cpsw1
Name Mtu Network Address Ipkts Ierrs Idrop Opkts Oerrs Coll
cpsw1 1500 <link#2>7c:38:66:26:ba:30 6412984 0 0 5694367 0 0
cpsw1 - fe80::%cpsw1/ fe80::7e38:66ff:f 0 - - 1 - -
cpsw1 - 192.168.1.0/2 shelter 5547 - - 2488 - -
There are no output packets for IPV4…</link#2></link#2></link#2>