My troubleshooting steps are always the same - review the logs, reproduce the problem on a test system, and go from there. From what I found on google, it sounds like the logs will answer your question though:
In the above scenario, it sounds like the problem was that the account was lacking connect permissions on the target machine. That error really means that something was replied back that doesn't make sense to Service broker. The ACTUAL error is on the other server/application that sent the request to Service Broker.
The above is all just my opinion on what you should do.
As with all advice you find on a random internet forum - you shouldn't blindly follow it. Always test on a test server to see if there is negative side effects before making changes to live!
I recommend you NEVER run "random code" you found online on any system you care about UNLESS you understand and can verify the code OR you don't care if the code trashes your system.