[HECnet] TOPS-20 on HECnet?

OK, I'm at the hair-tearing-out stage... Who here has a TOPS-20 system connected to HECnet? I'm trying to peer with Sampsa with "bridge" in his same area as an endnode. Bridge works fine on my end, lots of activity in debug mode, and I see lots of node number entries if I send it a SIGUSR1. However I never "see" the adjacent node in NCP, though my circuit and line are up and active. Adding a few nodes manually with NCP SET NODE and then trying a SET HOST in the monitor just times out. If I do this while watching my ethernet with tcpdump, I see my real DECnet traffic, immediately followed by its encapsulated udp packet going out over port 4711. However, I never get any responses to my SET HOST from the remote bridge side. Any suggestions on debugging this? Thanks, Mark