My tablet was doing it earlier today, 4G signal but no data being received, was just trying to send, I had to put it onto 3G/2G preferred to get internet. Meanwhile my CAT phone that uses Telkom SIM for data worked fine on 4G next to it.
If there is a DNS error it would mean you're connected to the internet but can't go anywhere where you use a name as it can't resolve the request to an IP. Could be a temporary glitch. You could also try to force the DNS servers to be 8.8.8.8 and 8.8.4.4 (google open dns) and see if that helps