I suspect your victory might be short-lived! Have you installed any Windows Updates yet? I'm still using MC23 but I have been having the same problem as you for the last couple of weeks. I also have several Jongo(s) and I found I could no longer get MC through the Windows firewall. Disabling the Private firewall has enabled me to keep playing music but I can't find a way to create an exception that works to allow me to turn the firewall back on. Like you, this not a new setup, nothing has changed here for at least a year, I'm fairly certain it's a Windows change which has been my downfall.
The 5 second delay is probably about right, there is a considerable delay on the Jongo(s) when they start playing, it probably takes this long for MC to get the feedback that the device isn't responding. I have reported issues in the past which resulted in the team J River actually buying a Jongo (thanks guys) and I remember they were distinctly unimpressed with the hardware, I think because of this slow response time? It's a dead technology anyway now but it was a shame as it can do some nifty stuff when you have multiple devices.
Maybe this will help to shine more light on the issue? Good luck!
Mark