I've seen this issue raised in JENKINS-11576 and a solution there. However, we're getting this

Fetching upstream changes from git@github.com:company/repo.git
ERROR: Problem fetching from origin / origin - could be unavailable. Continuing anyway
hudson.plugins.git.GitException: Error performing command: /usr/bin/git fetch -t git@github.com:company/repo.git +refs/heads/:refs/remotes/origin/
Command "/usr/bin/git fetch -t git@github.com:company/repo.git +refs/heads/:refs/remotes/origin/" returned status code 128: ssh_exchange_identification: Connection closed by remote host
fatal: The remote end hung up unexpectedly

at hudson.plugins.git.GitAPI.launchCommandIn(GitAPI.java:776)
at hudson.plugins.git.GitAPI.launchCommand(GitAPI.java:741)
at hudson.plugins.git.GitAPI.fetch(GitAPI.java:190)
at hudson.plugins.git.GitAPI.fetch(GitAPI.java:978)
at hudson.plugins.git.GitSCM.fetchFrom(GitSCM.java:765)
at hudson.plugins.git.GitSCM.access$100(GitSCM.java:80)
at hudson.plugins.git.GitSCM$2.invoke(GitSCM.java:1003)
at hudson.plugins.git.GitSCM$2.invoke(GitSCM.java:970)
at hudson.FilePath$FileCallableWrapper.call(FilePath.java:2196)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:326)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:636)
Caused by: hudson.plugins.git.GitException: Command "/usr/bin/git fetch -t git@github.com:company/repo.git +refs/heads/:refs/remotes/origin/" returned status code 128: ssh_exchange_identification: Connection closed by remote host
fatal: The remote end hung up unexpectedly

on a regular basis. As this is an interaction with GitHub the solution mentioned in JENKINS-11576 isn't an option.

Attempting the build will often, but not always, resolve the problem. This, however, wastes time.

Would it be possible to add a configurable retry to the code that executes the fetch?