Yes and no the chattr for the resolv.conf you can use however is on every OS.
Is the only part i can help , but i don’t understand your problem further.
"If you really aren’t using DHCP, my suspicion is that your provider is overwriting your resolv.conf file with a fresh one anytime you reboot. You may want to discuss that with them.
nameserver 127.0.0.1
to /etc/resolv.conf - than run this command
chattr +i /etc/resolv.conf
to make the file resolv.conf immutable (will no longer be able to be overwritten on boot)"