# ICE fails with server behind NAT, ONLY for some internal clients!

**URL:** <https://discourse.lynckia.com/t/ice-fails-with-server-behind-nat-only-for-some-internal-clients/652>\
**Category:** Support\
**Created:** [November 15, 2017, 4:27pm UTC](https://discourse.lynckia.com/t/ice-fails-with-server-behind-nat-only-for-some-internal-clients/652 "2017-11-15T16:27:54Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![mkh](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.lynckia.com/mkh/32/38_2.png) [@mkh](https://discourse.lynckia.com/u/mkh)\
**Post date:** [November 15, 2017, 4:27pm UTC](https://discourse.lynckia.com/t/ice-fails-with-server-behind-nat-only-for-some-internal-clients/652/1 "2017-11-15T16:27:54Z")

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The server is in a private network behind NAT. By setting the `publicIP` for both erizoController and erizoAgent in the Licode config, external users are able to connect to the server and publish/subscribe.

The problem is with some internal clients which are able to connect but can not publish/subscribe and get ICE failed while some other internal clients (with exactly the same OS/browser/config and in the same network) can! OTOH when I remove the `publicIP` then all internal clients are fine.

What would be the reason? I know using a TURN server may fix the problem but I’m curious to know why this is happening. How can I trace the issue? Any help would be appreciated.