I’m running a local server on Ubuntu 18.04 and was running in to a problem after my last Ubuntu server package upgrade. I just couldn’t connect to the Blynk server, not from the app and not to the server admin. At the end it I figured out that I’m wrongly accused Blynk local server to be the cause and found out that the Ubuntu update somehow had closed the necessary ports!
Solution, simply run those commands in Ubuntu terminal sudo ufw allow 9443 then sudo ufw allow 8080
At least this worked out for me
Kind regards/Stefan @ stockholmviews.com