Please note that the PepVPN (formerly site-to-site VPN) in the layer-3 mode does not support forwarding Bonjour packets. By default, VPN is set up in layer 3 mode. In layer-3 mode, packets are routed as IP packets between two different IP subnets, instead of being bridged as Ethernet packets (the subnet on both sides are the same).
As Kurt mentioned in the post you quoted, the VPN in layer-2 mode supports “bridging” all Ethernet packets including Bonjour. To enable it, click the “?” icon on the upper right hand corner of the VPN setting table. However this is going to be a major network infrastructure change. Unless you well understand what Ethernet bridging is, otherwise we don’t recommend you to do so.
We have a plan to support Bonjour over layer-3 VPN. Stay tuned.