f5 v12 wildcard destination port

You may have a monitor without an alias port assigned to that pool. Most monitors inherit not only address but also port data from the pool member; without a port specified in the pool member, one must be specified in the monitor or it will fail.

You may consider using an ICMP monitor for the associated node instead, but that's not a robust test of a TCP service. For an example of a monitor with an alias port see the built-in

https_443

Nope, that's not the case, at least not with my case. I do have alias port assigned to specific port. Taking an example for my Samba share, I have a virtual server listening to all the ports and so do the pool. But the smb monitor I have is associated with alias service port 445. But right after upgrading to version 12.0.0.0, I got the samba monitor down and service was down as well.

And yes, i do understand that I can still use the ICMP monitor but it is not reliable.

Thanks for answering and please let me know if something else I can try.

I didn't find anything, can you please provide a link?

OK, i think i got confused with FQDN, I am not using the FQDN but just the domain name. Any known issues with that?