IPSEC Issue

Hello All! I am not a packet analyst by far and I am trying to track down an issue we are having with IPSec and the creation of a secure tunnel over our network.

We have a dynamic port/address NAT rule in place that NATs all of the ip addresses in one location to a public IP address. We are trying to get a signal booster that is installed on our network to talk to towers outside our network. It looks like traffic is getting to the firewall but not the booster, but I have allowances on our firewall for ports 500 and 4500 and I can see that traffic is being allowed.

When I do a packet capture, (from the firewall) I can't read the results well enough to understand where the hangup is. I can see a packet that looks like it comes from our public ip address to the external address that is coming across as destination unreachable (port unreachable). The source port is ipsec-nat-t (4500). But does that mean that the firewall is blocking the port, even though traffic to and from that port is allowed? What should I be looking for to determine what the root cause of this stopage is?