Lync 2013 Server not working with iPad or iPhone clients

Good day to all, We have Lync 2013 installed. For the mobility (as TMG) ,

 I installed an IIS with ARR 2.5 , in order to use it as a reverse proxy.

So the topology is: One FE, one Edge, one RP.

I have autodiscovery implemented. Results are : PC login using Lync 2013 works properly from inside and outside.

 Android devices and Lync 2010 clients works properly from inside and outside. iPad devices on Lync 2010 and Lync 2013 and it does not work either inside or outside.

The error shows as Can't connect to the server. Try again later.

 In order to resolve the problem I was installing IIS Application Request Routing (ARR) 3 on Lync TMG server (the proxy one)