Error 503 Backend fetch failed

[ukfitnes]

I'm getting the following errors every time i try to save any WP settings, website is also down. can someone look into it please..
thanks

Error 503 Backend fetch failed
Backend fetch failed

Guru Meditation:
XID: 128614477

Varnish cache server


AND

Resource Limit Is Reached
The website is temporarily unable to service your request as it exceeded resource limit. Please try again later.