On Windows …:
PLINK.EXE is part of the PuTTY family, and it’s the utility tramp is communicating through. (You do know that, as tramp does not set itself up to make use of PuTTY.)
On all platforms:
Burying the tramp buffer in question is actually my 1st approach on all platforms (Linux/Mac/Windows), whenever tramp communication seems to be stuck. Afterwards with a “clean new start” everything is fine again in like 99% of the respective cases.
Sometimes only taking emacs down seems to solve the issue.