Multiple ldap servers in authentication source

Problem:
cannot login if ldap source server is not available

Expected outcome:
ldap uses dns autodiscovery, users login with srv dns query
Foreman and Proxy versions:

3.12
Foreman and Proxy plugin versions:

Distribution and version:
almalinux 8.10
Other relevant data:

I saw this other thread Allow multiple LDAP servers for a single authentication source

But it is not clear how to configure it. In the host field I used our sub.domain.tld name, but that does work (host name cannot be resolved); if I use host.sub.domain.tld it works, but then it is the same problem I now have.

It would like to have a ldap source that works even if one of the resolved hosts is not responding and without having to switch ldap sources for every user if the source is not responding.