So, first thing, need to understand if you are truly using VCS or Expressway. This can be accomplished with Webex Edge for Devices, but you need to be running Expressway proper. See help article here... https://help.webex.com/en-us/article/cy2l2z/W...
Honestly I'd start with the latest API reference guide on cisco.com to see if changes to the API has been made that would reflect the changes you are seeing. https://www.cisco.com/c/dam/en/us/td/docs/telepresence/endpoint/roomos-108/api-reference-gu...
Unfortunately with wireless there are a host of issues that could be causing this, anything from network drivers on the laptop to wireless interference... Does this happen with all different kinds of laptops and mobiles? Does it happen on WiFi as wel...
Without a license you would still able to register to a UCM or VCS to make calls, and you can whiteboard and send via email, you can also share content locally wirelessly using proximity or HDMI cable