Setting up HyperBackup to remote NAS for home users

I want to set up hyper backup between my NAS and a realatives so we each can have off-site backups.

We are home users and do not have domain names, just local home networks and DSL internet.

I'm following the steps in this article but it needs the destination IP. I was hoping that I could use quickconnect to avoid this.

https://kb.synology.com/en-global/DSM/tutorial/How_to_back_up_your_data_to_a_remote_Synology_NAS_or_file_server_with_Hyper_Backup

I can find the IP of our networks easily but we would still need to enable port forwarding. As the article says

The required ports for external access are:

6281 (Remote NAS device)

873 and 22 (rsync)

5005 and 5006 (WebDAV)

Is opening these ports safe? is there anything else I need to do to make sure I am keeping my NAS secure?