Custom app Error "connection refused to connect"

[htmlcssteam]

Hi,

I did create a custom shopify app.

And I was doing add script.js in theme when app install in store.

It is working. But after 1 day or 2 days it return error like "connection refused to connect"

After reinstall app it work like before but again issue come after 1 or 2 days

so can you please suggest solution for fix this ?