The customer reported this issue
from their Windows 10 v1909 laptop, connecting to a outsider vendors (OV) Windows 2016 RD Web Access box.
Before we get onto what the Outside Vendor recommended, here’s the fix I’d suggest:
Set the EnforceChannelBinding registry value to 0 (zero) to ignore missing channel bindings on the Gateway server. To do this, locate the following registry subkey, and use the given specifications:
Value: 0 (Decimal)
Note By default, the EnforceChannelBinding value does not exist on the Gateway server. You must create this value.
The Outside Vendor’s IT team advised: