iPad issues when connecting to ThingWorx app via VPN

Use case: iPad to access ThingWorx application via VPN.

VPN Client: F5

Navigate/ThingWorx Version 8.5.3

Tomcat version: 8

Tomcat access logs shows a HTTP Status Code: 400 when hitting the server via iPad ("-" 400 -)

Ports are open for inbound traffic.

What should I be checking?