We are observing the same problem on our server. Any job containing the word "plink" fails to clone. Since we are using a multi-branch pipeline, this causes any branch with the word "plink" to mysteriously fail.
The logs show this strange error message.
stderr: getaddrinfo: atch: Name or service not known
Then it tries to use the port from the URL as if were a hostname.
ssh: connect to host 7999 port 22: Success
I don't know how that connection could have succeeded. Then we get another error.
fatal: Could not read from remote repository.
See attached logs.