We have a BT Business Broadband hub 4, about a week ago the internet access stopped working. Eventually tracked the issue down to the DNS server IP that the hub was using, when the PC config was changed to use Google (184.108.40.206) rather than the one served by DHCP then our internet access was restored. The hub is set to use 220.127.116.11 and 18.104.22.168 as its default DNS servers. I think this is set when the hub powers up, but we can't find a way to reconfigure the hub to use any alternatives. Are these two DNS servers both working currently?
8 Strategies for Troubleshooting a DNS Failure
Restart Your Software or Device. Sometimes simply exiting the browser completely for a few minutes will solve the problem.
Restart the Modem or Router.
Pause Your Firewall.
Clear Your Cache.
Disable Extra Connections.
Keep Everything Updated.
Check DNS Settings.