This was exactly what I needed to solve a problem with clients connecting using a 5G router, that uses IPv6 address from the private IP range (fc00::/7) for DNS.Thank you so much for the "client-bypass-protocol" hint.
Thank for so much for this hint. Moved to VTI on a number of ASA units. Management access work on some units, but not all. Bouncing the management-access config, made them all work.