May or may not be applicable to your case, but often applications need additional configuration to work with a reverse proxy. Usually setting from what IPs it will accept forward headers from (your reverse proxy) and what the original requested host was (externally requested domain, eg: yourservice.yourdomain.com)
If your new setup has resulted in changes to either of those things, the issue might be a now-incorrect config of your apps behind the reverse proxy.
Reconnaissance-in-force