I also got same error couple of hours ago. Now it is working fine.
There were network issues in one of the Cisco firewalls for one of our datacenters. It's the only "Enterprise technology" we use for pginfra I think, and it does this every now and then. It was rebooted early this morning and then services recovered.
It would be great to have alerting tools like prometheus to notify users when the server is down
There were hundreds of notifications. But PostgreSQL does not have 24/7 staff (since it's all volunteers), so it takes some times to get things fixed. The issues started just past midnight, and were fixed at about 7:30AM.