Problem accessing NAS locally but not remotely via FTP

Hello. I have a NAS serving my library as FTP and I have no problem with it always I’m out of the house. If I’m in, it’s a lottery. Sometimes connects and sometimes does not saying that it couldn’t resolve the DNS and then I need to connect through SMB.

I use duckdns as DDNS and in my house I have pihole as well to resolve the dns. But I changed the DNS in the apple tv and I try with the cloudfare and google ones but still getting the same issue.

Anyone knows what is happening?

Thanks.

You may want to read through the users guide and see if there may be some help there.