I understand it may not be *just* you, but Google and Gmail is used by a gazillion folks around the world. So, odds are that it's not a Google issue.
So you back up and start debugging things that way.
Agree with flushing DNS cache.
Other ideas:
- use Google's DNS servers: 8.8.8.8 and 8.8.4.4
- how are you connecting to the net? Starbucks Wifi or cell hotspot. Try different connections if possible
- if you know how to do traceroute, you can see all of the hops between networks can carriers that outline the path between you and Google. The blockage could be anywhere in there
IIRC the last time Gmail had an outage was 2014. And it made the news. So, again, the debug supposition would be - assume it's not Google and start at your PC and work forward.