Please make sure cache and cookies are cleared, and make sure all sites are marked as safe trusted sites. If this does not work, please set his DNS to a preferred address like Google’s (8.8.8.8)
If none of these correct the issue could you have the provider try from a separate computer (on a separate network)?
Control panel > internet options: privacy/advanced makes sure 3rd party and 1st party cookies are set to accept then click ok. then X out.
Network and Sharing Center > change adapter settings
Right click on ethernet, properties, internet protocol version 4, properties, in the bottom section, click Use the following DNS server Address, change the DNS settings to 8.8.8.8 click OK then click close.