A form submitter is getting a connection problems in the form

We have someone who is having issues with submitting to the below form. Could it be a browser issue. He said it is saying connection problems but he gets to the last page ok

It's probably a network issue between the user and the form. Especially, this is a long form and you have a file upload fields in the form.

Please try asking the user to check the browser console for possible errors. After getting the error, simply press F12 in keyboard. Find and click the "Console" tab.