Can you ping 88.102 from a .77 address, and 88.101 from a .99? If it's working when you enable the ICMP checkbox then perhaps you're just missing a firewall rule on each UTM allowing Ping between your internal networks.
Can you ping 88.102 from a .77 address, and 88.101 from a .99? If it's working when you enable the ICMP checkbox then perhaps you're just missing a firewall rule on each UTM allowing Ping between your internal networks.