From your comments, you look to have your devices registered to Webex Control Hub through Webex Edge for Devices. As you are running CE220.127.116.11 (which will be on the DX80) and RoomOS 10.4.1.1 (which will be the Webex Room Kit), you look to also have Cloud Upgrade mode enabled.
Can you advise as to whether you have the Webex Optimized Experience enabled (Webex Join Protocol set to Webex (default is SIP)) and have rebooted since setting this?
If the Webex Optimized Experience is enabled and you are not able to connect to a Webex Meeting by pressing the Join Webex button and entering the Personal Room, Meeting Number or Meeting address, then this could be a network restriction that you are facing. Webex Edge registered devices with Webex Optimized Experience running will want to route media direct from the endpoint to the Webex cloud. It will not traverse your Expressways/VCS architecture.....so you need to ensure that the networking requirements are met to allow the endpoint to join. For example port 5004 SRTP over UDP
Hi, so you should only be seeing traffic going to or from Webex on the Exp-E/Exp-C pair if
Webex Join Protocol is left as default (SIP is default)
Webex Meeting App has requested a callback to the SIP URI of the endpoint
TMS has been used to autojoin the device to the meeting (TMS would define the call protocol during setup and is not aware of Webex Join Protocol - this would cause the device to join as SIP even if Webex Join Protocol was set to Webex)
Short cut code dial - for example you have specified that users dial *444 followed by meeting number
If Webex Join Protocol has been set to Webex, then an action from the endpoint that resulted in the device calling into the meeting would mean a direct media path from the device into the Webex meeting and no media should flow through Expressway pair.
Proxy details are shown in the network reqs link I shared