[HECnet] DECnet-Plus and Decnet Phase IV interoperability

Hi Recently I cloned one of my MicroVAX 7.3 simh servers and removed DECnet phase IV from it (which works perfectly) and installed DECnet-Plus from the distribution. I set it up with the same details as for Phase IV and configured the same MAC and area/node - clearly I will not boot both at the same time! The simh setup is identical for both version of the server apart for my having increased memory from 128M to 256M to see if that helped (it didn't). It sort-of works, there is connectivity and adjacencies as I would expect but it is extremely slow. If I "set host" to another machine, or from another machine to it, it works extremely slowly, I see 3 second retries happening all the time. The command "SHOW NSP LOCAL NSAP <local_nsap> REMOTE NSAP * retransmitted pdus, duplicate pdus received" suggested here https://community.hpe.com/t5/operating-system-openvms/very-bad-performance-o ver-native-decnet/td-p/5000605 shows the retransmit count going up. The adjacencies are on ethernet LAN - has anyone got any experience of this problem which might suggest what is happening? Thanks Peter Peter R Whisker BA BAI CEng MIET Chartered Engineer - IT Technical Architect T: +44 1932 842536 M: +44 7870 171768 E: peter(a)whisker.org.uk