Trying to connect to AnyConnect - with DUO - Getting a 404 error

My employer recently implemented DUO MFA for remote access. Previously, it was just an AnyConnect VPN concentrator.

I use Ubuntu (18.04) on my personal computer at home and previously had no problems. Now I get a 404 message when trying to connect in the network manager screen. I have attached the tail end of the log output below. An insight would be appreciated as they do not support Linux.
Got HTTP response: HTTP/1.1 404 Not Found
Cache-Control: no-cache
Pragma: no-cache
Connection: Close
Date: Wed, 18 Mar 2020 00:49:41 GMT
X-Frame-Options: SAMEORIGIN
HTTP body http 1.0 (-1)
SSL socket closed uncleanly