Two issues, possibly linked in some way. First is, VPN clients are showing their local IP and VPN IP (from ASA) in DNS i.e. 10.255.253.1 and 10.255.240.51 This causes issues connecting to the VPN IP 10.255.253.1 beciase of 2 DNS entries. Client on the LAN where the DHCP/DNS servers reside work fine. Only affect VPN users.
Other problem is that when clients are not showing the local IP of their WIFI card in DNS and showing the correct IP (it was working at some point previously) we cannot browse to that machine, so remote management doesnt work.
No 10.X.X.X address will ever work with a VPN or any other tech, for any machine outside the 10.X.X.X related LAN.
Said another way, there are 1,000,000s of 10.255.240.51 addresses active at any given moment all over the world, on many LANs so routing packets outside any LAN to any instances of this IP makes no sense.
https://en.wikipedia.org/wiki/Private_network provides more detail, along with additional resources for research.