Fasthosts & Cloudflare issues

Has anyone experienced or know if there is a continuous problem with Fasthosts shared servers working with Cloudflare? I have spoken to both companies at length about 521 errors which occur on our website about 2-3 times per day. Both blame each other:

Our shared servers do not restrict any IP addresses.

A 521 error happens when we are unable to make a TCP connection to your origin server, typically because the connection was refused which often can be caused by security or firewall software.

We keep going back and forth with both companies sharing replies from one company and sending to the other.

Both have checked log file but can’t see any errors, but we know the site goes down as we are sent emails about it from Cloudflare everytime it happens.

Cloudflare have asked me for instructions on how to replicate and HAR files, but how can you replicate a server error as it is intermittent.

If anyone has had these issues or might know what we can do then please let me know,


I’m going to give @chasers a shout because I’ve always wondered if Logflare has any insight into the origin connection. Without full access to all logs, these errors are really tough for customers to track down.

If you could that would be great, thank you

Hey sorry for the delay here!

You should setup Logflare to see exactly how often and when those happen, and that’ll give you the request / response headers of the request also.

Once you have this you could setup something on the backend to send over custom response headers depending on where it is in the pipeline perhaps? That will be highly dependent on what you can actually do with Fasthosts.

But there may be at least a request ID in the response headers which you can give to Fasthosts to debug. There should be something like that but who knows.

You can also give Cloudflare the ray ID, which you can find in the request headers after you install Logflare.

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Hi, thanks for getting back to me. I’ve set up Logflare, but im not really familiar with everything you’ve spoken about.

Fasthosts have now asked for a traceroute which i have done and sent to them so will see what they say.

I’ll see what Logflare shows in the next couple of days and ask Fasthosts if they can use any of the information to debug, do you think that is the best thing to do considering im not as technically minded as this may call for?


Give Logflare a couple days to get data and then you can do a search for metadata.response.status_code:>499 which will give you all 5xx responses. And then click the metadata link next to the one in question to see all that request data. If you’d like to email me ([email protected]) I can help see if there is anything useful in there.

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