Cant really see the screenshot (pixely) but try pinging the FQDN of the KMS Host (yourservername.yourdomain.com) and see if you can ping it. Even though it's published in VLMCS maybe the clients aren't able to hit it because they can't resolve the FQDN.
Also, did you try manually pointing the clients to yourservername.yourdomain.com in VAMT or by slmgr -skms.. Did it work this way? If not, then definitely try pinging the FQDN as it could be the same issue (no static IP or other DNS issue).
