Dialin and meet showing up as blank page externally but works internally just fine

Question

if i go to dialin.domain.com and meet.domain.com externally, then i get a blank white page no matter what browser i use. i can see the cert in the browser just fine. internally, dialin and meet work fine. i'm using IIS ARR for the reverse proxy. i can telnet
to dialin.domain.com and meet.domain.com over 443 just fine externally.
i used http://jaapwesselius.com/2014/03/16/using-arr-for-reverse-proxy-with-lync-2013/ to setup IIS ARR.
please help.
thanks in advance for your time.

Answer 1

i'm getting this with the remote connectivity analyzer:
Testing connectivity to the Lync Autodiscover Web Service server for a secure connection on port 443 to obtain the root token.
Connectivity to the Lync Autodiscover Web Service test failed.
Additional Details
Elapsed Time: 1078 ms.
Test Steps
Attempting to test Autodiscover Web Service URL https://lyncdiscover.domain.com/Autodiscover/AutodiscoverService.svc/root.
Autodiscover Web Service URL can't be contacted due to failure of the following tests:
Additional Details
Elapsed Time: 1078 ms.
Test Steps
Attempting to resolve the host name lyncdiscover.domain.com in DNS.
The host name resolved successfully.
Additional Details
Testing TCP port 443 on host lyncdiscover.domain.com to ensure it's listening and open.
The port was opened successfully.
Additional Details
Testing the SSL certificate to make sure it's valid.
The certificate passed all validation requirements.
Additional Details
Test Steps
Testing HTTP authentication methods for URL https://lyncdiscover.domain.com/Autodiscover/AutodiscoverService.svc/root/user.
HTTP authentication test failed.
Additional Details
A Web exception occurred because an HTTP 502 - BadGateway response was received from Unknown.
HTTP Response Headers:
Content-Length: 0
Date: Mon, 13 Apr 2015 17:29:25 GMT
Server: Microsoft-IIS/8.5
Elapsed Time: 275 ms.