gmubnt.co.uk has an A (IPv4) record (208.167.245.8) but a request to this address over port 80 did not succeed. Your web server must have at least one working IPv4 or IPv6 address.
Get http://gmubnt.co.uk/.well-known/acme-challenge/letsdebug-test: dial tcp 208.167.245.8:80: connect: connection refused
Trace:
@0ms: Making a request to http://gmubnt.co.uk/.well-known/acme-challenge/letsdebug-test (using initial IP 208.167.245.8)
@0ms: Dialing 208.167.245.8
@2ms: Experienced error: dial tcp 208.167.245.8:80: connect: connection refused
A test authorization for gmubnt.co.uk to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
Fetching http://gmubnt.co.uk/.well-known/acme-challenge/ZHdEBY7NuzhmHEzLDTVh5V5NkxSvwQMC_JiRA7UhBu0: Connection refused