I just started using Notebooks in ArcGIS Online and I have created/saved my first notebook - it is a work in progress. While working in it, the kernel disconnects frequently - roughly every 10 minutes or so. When this happens I get the standard error message that the kernel has been disconnected and that I should restart the kernel. None of the kernel restart buttons that are available have ever restarted the kernel, it just remains disconnected. My only recourse, that I know of, is to refresh the browser tab for my Notebook, and when it loads again the kernel is active/idle.
There must be a way to get the kernel to remain connected, right?
Did you ever figure this out? This happens to me all the time. Now I'm saving my work often, but occassionally I'm working on changes I don't want to commit, so having to save all the time is not convenient.
I never learned of any way around this behavior when using the AGOL Notebook and sounded to me that it is just the nature of the product (being in the SaaS enviro). Like you I save constantly while i am adding anything into it. I also keep Notepad open nearby for the occasional pasting of test script - just in case.