This topic came up on the alt.sys.pdp10 list
https://groups.google.com/g/alt.sys.pdp10/c/ZttQxHZGEJQ
Apparently DECnet-10 won't work past November 9th 2021, which isn't that far
away. Personally I'd never heard this before and had no idea, and since I
know there are a few 36 bit emulations on HECnet that are obviously using
DECnet I thought I'd pass it along.
TOPS20 isn't explicitly mentioned, but I'm guessing that it has the exact
same issue. That'd mean no DECnet on 36 bit systems after next year!
Unless, of course, you want to start playing games with the date (which I
hate doing).
Bob