The Pop-up message "Connecting to replicon, please check your internet connection" is a feature within Web Timesheet. This could show up for various reasons. Below are some of the scenarios when this pop-up message appears.
When a user's timesheet has too many rows (especially with projects), Which adds-up to the delay in loading the timesheet.
Due to bad browser cache or cookie.
The timesheet has a built in auto-save mechanism, which kicks in when the user has not saved the timesheet for a long time, you may notice the pop-message.
In case you notice this pop-ups frequently or unusually please feel free to raise a request to Replicon support, such that this issue can be debugged in more detail.