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ERR_CONNECTION_REFUSED The connection was refused
What it means
Something at the address actively refused the connection. That is different from a timeout. A program was there and said no, often because nothing is listening on that port, or a firewall rejected the attempt with a reset.
Where you usually see it
Local development servers that are not running, a typo in a port number, and hosts where the web service has stopped.
What to try first
If this is a site you run, check that the web service is running and bound to the port you are calling, including the difference between 80, 443 and a development port. If this is someone else's site, wait and try later; you cannot open a port on a machine you do not control.
When to stop
A refused connection is not a certificate problem and not a typo in the page path. Do not keep retrying in a tight loop against a machine you do not own.