public IP address caching?

running a 'what is my public IP' tool, we're struggling with reliable client IP detection, maybe due to some weird public IP address caching issues or stale X-Forwarded-For headers from certain CDN edge nodes. this leads to wrong public IPs for users. here's an example of what we're seeing:

Request Headers:
  X-Forwarded-For: 192.168.1.1, 10.0.0.5
  X-Real-IP: 10.0.0.5
  (Expected public IP: 203.0.113.45)

how do you guys reliably get the true client's public IP when these X-Forwarded-For chains are unreliable or truncated, especially if caching is involved? help a brother out please...