We were using an on-premise Lync 2013 Server for the last 2 years. Now that our group has merged with another group, we chose to go 'cloud' with them.
So what we did was to change our local split-DNS and external DNS entries, according to documentations found on some office365 websites.
BTW Exchange works fine for everyone.
Most of our users are connecting to Skype for Business Online, but at some locations, our employees cannot. They are all getting the same error regarding DNS
(I'll replace our external domain name for contoso)
"Can't sign in to Skype for Business"
"Skype for Business couldn't find a Skype for Business Server for contoso.ca. There might be an issue with the Domain Name System (DNS) configuration for your domain. See KB2566790 for details and contact your system admin."
Every locations has a DC with DNS server role. So I've checked our internal DNS servers, to make sure everything was replicating fine, and it does. All our DNS servers have the following entries regarding Lync
Forward Lookup Zones
name: lyncdiscover Type: CNAME Data: webdir.online.lync.com
name: sip Type: CNAME Data: sipdir.online.lync.com
name: _sipfederationtls Type: SRV Data: sipfed.online.lync.com (5061)
name: _sip Type: SRV Data: sipdir.online.lync.com (443)
If I run a ‘lync connectivity analyzer’ on problematic workstation, I get the following error:
Server discovery failed for unsecured external channel against http://lyncdiscover.contoso.ca/
I attached the log file.
Thanks for any help you could provide