ASN Lookup Reliability Issues

Hey everyone, I'm working on our tool, 'What is My ISP? - Find Your Internet Service Provider,' and it's heavily reliant on providing highly accurate and consistent IP data, particularly around identifying the actual Internet Service Provider. Our primary method involves robust IP geolocation and subsequent ASN lookup to map an IP address to its owning entity, which ideally should be the ISP. We've built a pretty solid foundation, but we're hitting a wall with the consistency and accuracy of ISP identification, especially when it comes to the nuances of ASN lookup data. The discrepancies are particularly noticeable across different IP types – residential IPs, dynamic IPs, and especially those behind VPNs or proxies, where the reported ASN might belong to the VPN provider rather than the end-user's actual ISP. This becomes a major headache for our users who expect precise information about their connection. We've certainly tried a range of approaches to tackle this. Our current stack leverages several commercial IP geolocation APIs, direct whois queries against regional internet registries like RIPE, ARIN, and APNIC, and even some custom parsing of public BGP routing tables. While these methods provide a good baseline, they often fall short in edge cases. For instance, a residential IP might show an ASN belonging to a very large backbone provider, but not the specific local ISP, or the data might be stale. VPNs and proxies are another beast entirely; while we can often detect the proxy, accurately identifying the underlying ISP behind it, even with a secondary lookup, remains elusive. We're constantly chasing down inconsistencies where different data sources return conflicting ASN information for the same IP, or where the ASN description is too generic to pinpoint the actual service provider. I'm really looking for some advanced solutions or perhaps less conventional data sources that could offer more robust and reliable ISP identification, specifically improving our ASN lookup accuracy. Has anyone here had success with alternative network intelligence platforms, or perhaps techniques involving active probing (ethically, of course) or leveraging obscure routing data sources? We're trying to push the boundaries of IP geolocation accuracy for ISP identification. Specifically, what are the best practices for handling large IP ranges and subnets when correlating ASN data with actual service providers, especially for global coverage? Are there particular pitfalls when trying to distinguish between a transit provider's ASN and an end-user ISP's ASN, or specific strategies for dealing with enterprise networks that might use their own ASNs but are still behind a larger carrier? Any insights on how to more effectively disambiguate between ASNs representing the true ISP versus those belonging to intermediate networks or data centers would be invaluable. Help a brother out please, this is a deep rabbit hole!