CDN says host down yet it's up

This keeps happening every now and then and it only happens with a wordpress site.
The CDN will say the host is down on Chrome for example yet it’s up on firefox.
Does not matter if it’s the front end or back end, on which ever browser the problem is happening, it happens until I disable the CDN for a wihle then re-enable it.

This is quite frustrating while trying to get some updates completed.

What could be causing this?

May I ask if you got some report from Cloudflare about it, or some other CDN you are using?

What is the error?
Is Cloudflare allowed to connect to the origin/host server?
How do you check or know it is down or not? Do you use some monitoring tools?

Kind a weird behaviour.

Maybe Cloudflare is blocking or not working over some port that is needed to update due to not being compatible port with compatible ones as listed on the below article?:

Or, maybe some Security option is being enabled at Cloudflare dashboard which could potentially block the update(s) process?

Hi, it’s a cloudflare page that shows up

Not sure what you mean by is it allowed, it’s a poublic web site so yes, it’s allowed.
I know because we have monitoring that tells us immediately if a web site is not reachable. We also check via ssh if something seems odd and we can use something like this to see if it’s up in real time.
https://www.dotcom-tools.com/website-speed-test

Yes, very weird behaviour for sure.

No special ports are in use. Just a normal port 80>443 site and like I said, it’s fine on one browser but not the other. Clearing the cache in the browser is not an option because I always have over a hundred tabs open and don’t want to get logged out of everything I’m working on.

Wow, my reply was completely gone after I typed it all and hit Reply. Trying again.

The error is from CF itself. See image.

We have various monitoring tools that tell us when something is down including www.outages.io, zabbix agents and always have ssh access to the servers. We can also use something like Free Website Speed and Performance Testing | Dotcom-Tools to check in real time if something is up or down.

And more importantly, it’s down on one browser but up on another. This means to me some sort of caching issue with the browser but I cannot easily clear the cache since I always have over a hundred tabs open to stuff I’m working on and would get logged out.

We use no special ports or security, just port 80 forwarded to port 443, pretty standard.

Unreal, a service as huge as this censors if you post links to anything. So greedy.

The error is from CF itself. See image.

We have various monitoring tools and always have ssh access to the servers. We can also use online tools to check if the site is live from different places around the globe.

And more importantly, it’s down on one browser but up on another. This means to me some sort of caching issue with the browser but I cannot easily clear the cache since I always have over a hundred tabs open to stuff I’m working on and would get logged out.

We use no special ports or security, just port 80 forwarded to port 443, pretty standard.

Try access the URL path www.yourwebsite.com/cdn-cgi/trace on both browsers and see what information you get.

Wish I could understand why my post was censored. Plenty of people post links to other sites, I see them all the time when searching Google and finding posts on this site. I wish big companies were not so greedy that they don’t allow others to be mentioned as it stops innovation in my opinion. We all want to learn about new tools, not be blocked/censored or hidden from them.

I’ll have to keep this post link in my notes and update it when it happens again.

This morning, it’s fine now and this is how it goes. Rather frustrating to have to disable the CDN, wait an unknown amount of time to be able to reach the site and once done working, re-enable the CDN.
The only other way is to use a machine on the same LAN which has direct access but we’re usually not on the same network.

I’ll update this using your suggestion when it happens again. Thank you.

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And today, it’s the other way around. firefox is now breaking while chrome is doing just fine.

fl=81f4
h=www.domain.com
ip=x.x.x.x
ts=1622132639.768
visit_scheme=https
uag=Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0
colo=LAS
http=http/2
loc=US
tls=TLSv1.3
sni=plaintext
warp=off
gateway=off

The odd thing is that it shows the site all broken one moment, then shows the CDN host error page.
Nothing wrong with the server, it’s up, running, I can see the apache logs, it’s taking connections, however, perhaps broken for those clients.

Why can’t I edit my posts?

A few moments later, I and I clicked on the logo even if the page was broken and got to the top of the site.
It kept showing the page broken, then the CDN error and finally the page cleared up. I went back to the page I was working on and it happened 3 or 4 times until it finally cleared up and now the page is showing as it should.

Absolutely something on the CDN side since I made no changes what so ever here and can see the web services are up and running taking connections.

I’m seeing a pattern. It definitely happens when we are editing pages or have saved the changes. It seems the CDN gets confused or something and either shows broken page or host is down which it is not.

How do you mean?
Do you have some caching in between?
Are you trying to ping your HTTPS Website or ping your IP address of the origin host/server instead (not pinging the Cloudflare IP)?
The error 521 or some other too?

If so, check here:

The Cloudflare or some other CDN?

Are you serving your WordPress Website over HTTP or HTTPS?
Any mixed content errors?

Why can’t I edit my posts
I meant here, in these forums. I have no option to edit posts once I hit reply.

Everything is always https.

Do you have some caching in between?

No otherwise I would have checked that too.

Are you trying to ping your HTTPS Website or ping your IP address of the origin host/server instead
(not pinging the Cloudflare IP)?

I have two browsers up so can see when one works and the other does not. I am SSH’d into the server so can clearly see the services are up, the can see the logs.

I’m not following. Ping? I know when the CDN is caching or not. When it’s caching, I can see the CDN IP’s hitting the apache logging. When the CDN is off, I can see the hits direct.

What do you mean by switching to ‘standard’? What I’m explaining is that when we edit some pages on the site, this is when it seems to happen. Since there is no caching on the server side, it means that the CDN is for some reason not able to understand that we made a change or something and so decides to show an error.

The new pages/posts that we make definitely show up but as soon as I refresh the page from the browser that is going through the CDN, things break as explained above.

The error 521 or some other too?

Always the same, wrong host down notice from CDN. No other errors can exist since the site is in fact up and running and cloudflare is wrongly telling our visitors that we are down.

I really don’t want to have to clear the cache every single time we update a page. Maybe there is something in Apache that could tell the CND when to update the page, etc. I’m sure I’ve seen/used such directives in the past.

Hm…

Usually, I have selected the “Cache Standard” settings for Cache at Cloudflare dashboard.
Morover, I have selected “Respect origin cache-control” selected and having the needed HTTP headers setup at my server to control it.

When doing some modifications, I call the file like for example style.css?ver=someinteger for CSS.

That way, each time I modify/alter it, I manually change the value and that way the end-user Web browser has always have to download a new one due to the “query” part of the URL for the resource file.

  • the naming as changing the integer value can be done automatically

But, I am afraid that’s not actually the way or the solution to your issue as far for now.

I can confirm it’s when I update something on the site. I just tested that and it happened.
In fact, I changed the published date of an article and sure enough, the CDN shows host error.

Even crazier now. I cleared the cache and even disabled the proxy and the browsers are still both showing that the host is down. What a mess our visitors must be seeing if they had something cached before.

There is no caching on the server side, only mod deflate and mod expire. Perhaps mod expire is causing an issue.

I wish I could edit my posts here as I am ending up posting a ton of short comments.

Anyhow, I found this, would anyone know if this would help?

Not really, you just ran afoul of discourse trust levels, Understanding Discourse Trust Levels | Blog. I bumped your permissions a bit so that you won’t hit the TL0 limits.

Same TL0 limit on edits after 24 hours,