Strange proxy routing led to network & reliability issues


we just disabled Cloudflare for our two websites (different account, though - cannot log in to the forum with my ‘normal’ account).

Reason: we suffered from strange timeout issues (not on server side, but on client side) when doing REST webservice calls. I was not able to replicate the same issue when only web surfing the site.

Here is the situation
I am located in central Germany and on our business site, we had constant issues for days getting responses from REST web service calls. We experienced the same every now and then for a few times but this time, it was 100% for days, disrupting our business.

Strangely, I was not able to reproduce the issue from my private location, which is why I attributed this to some issue with the ISP at the business location (German Telekom).

While testing, I also tested with my mobile hotspot (Vodafone business) and surprisingly got the same issue: none of the REST calls returned successfully, even though on server side the log did not show any issues and even reported the request had been completed.

Thus, I now had two major ISPs with the same issue, while only one (Vodafone cable at my private place) without.

After hours and hours of digging, it turned out that the DNS lookup of our web site returned different sets of IPs depending on which IPS I was using.
Vodafone mobile and Telecom DSL returned the same two IPs, while my Vodafone cable returned a different one.

Whenever we did a REST call through the first set of IPs, it failed, while it always went successful when using the other.

Not knowing how and where to address this (no pro-account, yet) we decided to remove Cloudflare from our DNS in order to stop it from blocking our business.

Today, I checked the IPs which were returned by making the DNS lookup.

On my private site, both IPs belong to a data center in Amsterdam/Netherlands which is quite close to my location. This makes perfectly sense.

On the business side and on Vodafone mobile hotspot, I received two IPs seemingly from the US.
Guess my surprise.

That still does not explain the network issues per-se, but it is very, very weird.
We were thinking of going Cloudflare Pro but this unreliability with the two by far biggest IPs we have in Germany really struck me.

Does anybody have an explanation for why
a) we might have received IPs from the US
b) the IPs might have caused the REST response issue?

And where would I normally address these things?
I mean - this is a really, really serious routing and reliability issue which usually stays completely undiscovered.


PS: when I refer to ‘business site’ I mean the physical location, not the web site :wink:

PPS: text autocorrection… IPS and IPs mean ISP… (internet service provider)

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