I've been puzzling over this for days and have come to a complete dead-end.

I have a couple of Synology NAS's in different locations.  I'm trying to get a hyper backup going from one NAS to the other using a reverse proxy.  The backup works just fine without the reverse proxy - using port 6281 which has been port forwarded on the destination router.

Reverse proxy works just fine for logging into the web server - using port 443 as the source and port 5001 as the destination - with port 443 forwarded on the destination router to the local ip address of the destination NAS.

However, a similar approach for hyper backup throws up the following message:

"Failed to connect to the destination server. Please check the following and try again: The destination server is connected to an active server (which it is!), The network backup port forwarding rules have been configured on the destination server (port 443 has been forwarded on the destination router to the local ip address of the NAS).

The firewall rules on the destination NAS have been changed to allolw ports 443 and 6281 through (I have also turned off the firewall on the destination NAS, but this makes no difference).

The certificate on the destination NAS has been obtained from Lets Encrypt - shown on the default certificate as hyper.xxxx.synology.me, including a wild card *.hyper.xxxx.synology.me.

My router is an Edgerouter - I haven't changed any of the standard settings, except the firewall portforwarding rules - in particular forwarding port 443 and port 80 (both protocols) to the local ip address of the destination NAS

Can anyone help please - I've spent too much time on this to give in now!!