'There is a Connection Issue'. Hmm, looks like there's no connection. Try reconnecting or come back later.

Error occuring:

 'There is a Connection Issue'. Hmm, looks like there's no connection. Try reconnecting or come back later.

Solution:

In button configurations, if your button have been configured with pre-chat page form page/URL

Remove the pre-chat form page on the selected chat button 

Steps:

Salesforce Classic - Setup  | Chat Buttons & Invitations | remove as mentioned and Save

Salesforce  Lightning - Setup | Find and select 'Chat Buttons & Invitations' | Edit the respective button and remove the pre-chat page form page/URL as mentioned