Blocked IP addresses of an ISP


I’m working in an ISP as an a network administrator. We use CGNAT to provide internet services to our customers. ~250 users are NAT-ed to one global IP address. Recently some of our customers started complaining about some Android/IOS apps that were not working properly. But when they change the network to cellular network it works like a charm.

I started investigating the problem. The routing part was OK. Those apps also had Web pages. When I tried opening those pages from the laptop of the complaining customer I immediately noticed the problem. The page asked mo to complete the CAPTCHA. I’m pretty much sure that that’s the very same reason of why the mobile devices could not work.

I tried to contact those companies for whitelisting our IP addresses but without luck. What can I do about it as an ISP worker? As you may already know I (and I guess the rest of the world too) don’t have any choice other that deploying NAT at the moment. And NAT provides us with such problems. Any help is appreciated!

There may be a malicious device behind your NAT:

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