Hmm, I can only assume that this isn’t working because I’m running node.js from the official Docker container. But on the flip side I’ve got the container set to use host networking, so it’s not like anything should be unintentionally blocked by the use of Docker.
I tried installing node directly on the server itself (a Synology NAS) using Synology’s own package, but there’s too many components missing to allow the npm install script to complete. Seems like it would be far too much extra work to get that working, when the Docker image appears to be working fine.
Any ideas of anything else I can try?
Edit: Possibly answering my own question: Turns out that Docker doesn’t pass multicast to containers so doesn’t work with SSDP, however, using host networking should apparently work around that, so I’m still at a loss.
Edit 2 (cos I can’t post more than 3 replies right now): Fixed it! The problem wasn’t Docker, but my ASUS router. Had to turn on “Enable multicast routing (IGMP Proxy)” and “Enable efficient multicast forwarding (IGMP Snooping)”, which is found under LAN/IPTV settings of all places.
If anyone else is having discovery issues, check your router for IGMP settings and enable them!