I greatly dislike when I find a forum post with no answer so I will answer what the final solution to this was.
I had done some digging into the UAG console and noticed the below messages. From what I had gathered the UAG has a built in mechanism that protects itself from DDOS type attacks. Our Citrix Netscaler Load Balancer health check was triggering this mechanism. So essentially the UAG thought the Load Balancer was attacking it so it shut itself down. The DosPreventionHandler kicked in. Port 4172 (PCOIP) remained open, existing users remained connected, but port 443 stopped accepting new connection. When I spoke to VMWare support they confirmed my suspicion.
The workaround is to set the below settings to 0 in the UAG.
