I have finally found a solution, but it requires ideally a VM with multiple network interfaces. Some background. I have P1S in LAN Only Mode on a VLAN with No Internet Access. I have my clients I like to slice/monitor from on another VLAN that does have Internet access, etc so by default the SSDP discovery doesnt work for Bambu Studio/Orca Slicer.
I already have a Ubuntu Server VM running Avahi for mDNS reflector, so it has multiple interfaces on different vlans and i use that for the reflector.
I found a package on Github (GitHub - marjohn56/udpbroadcastrelay: UDP multicast/unicast relayer) and you can use it to relay the SSDP (UDP 2021 for LAN Only Mode in the case on BBL) to another interface.
I used the command: udpbroadcastrelay --id 1 --port 2021 --dev ens36 --dev ens35 -d -f. I made mine run as a service so it starts with the VM, but so far it’s been working great. Change the Dev ports to your network interfaces (1 interface on same network as Bambu, and 1 interface on same network as your clients).