AG listener with MultiSubnetfailover True on Named Instance

I have an AG configuration with databases on a Named instance. I have enabled multisubnetfailover =true and registerallprovidersip =1. I just saw some blurb on the web that these settings are not supported by Named Instances. Has anyone used these settings on a named instance and had a successful fast failover from 1 subnet to another? confusing links https://johnlouros.com/blog/leveraging-multi-subnet-failover https://www.sqlshack.com/sql-server-always-on-listeners/