pfSense access through Synology reverse proxy?

[Cabledude]

Hi all,
In order to access devices on my home network while off site, I have set up a reverse proxy on my Synology NAS in conjunction with a dedicated domain name. I thought HTTPS is plenty secure. This works perfectly, but not for pfSense.
I have added several subdomains such as "syno" for the Synology GUI, "drive" for synology drive, "unifi" for the cloud key etc.
When I try to set this up for pfSense, I get a security error message. Is there a way to accomplish this? Or is this a bad idea to begin with?
I also have a RA VPN running on pfSense so I can connect to the pfSense GUI quite easily.

Thoughts?

Thanks,
Pete