504 Gateway Time-out

HTTP/1.1 503 errors due to backend fetch (restarted 4) varnish 6.2 ?????? IP: 6-85-52 Date: Sat, 10 Aug 2019 06:19:15 GMT Content-Type: text/html; charset=utf-8 Content-Length: 990 Connection: keep-alive Server: Varnish X-Varnish: 478446258 500 errors due to backend fetch varnish level 1 (from Varnish 6.2) - ho humm error - IP: 6-85-52 - 503
Synth - !AMP - 500 errors due to backend fetch (vcl_synth - 500-700) varnish level 1 (from Varnish 6.2) - ho humm error - IP: 6-85-52 - 503