How to set Reverse Proxy (Synology NAS DSM 7.0) so that Nextcloud sees originator IP and not NAS ip

Hi, can someone please help me? I need to set my Reverse Proxy in my Synology NAS so that my Nextcloud instance sees the originator IP, and not the Reverse Proxy IP as it currently is doing.

I’m guessing I need to add a custom header, I just don’t know how to type it.
I have 2 fields, one with ‘Header Name’, and the other with ‘Value’.

Thanks for any help

Is this helpful to you? I’m messing with reverse proxy as well, but my problem is I can’t figure out how to add it into Trusted Domains without borking everything