@vacquah While it works, the Synology does not seem to automatically update the certs even though it is supposed to. I do get a reminder so can manually get it to update.
On the synology side you need to set it up with the certificates part on the control panel. There are plenty of web hits on how to do this part.
The HAProxy part is basically how I have it in a few posting before this. You need to be careful of the order of things as I had my pfSense path first and it was matching that and going there and never got to the synology match. After a reordering it worked as it should.