Lync getting blocked by Sonicwall Proxy Access

Lync getting blocked by Sonicwall Proxy Access

This one is hopefully pretty rare, but I was having issues logging clients into Lync online in their domain environment while outside access worked fine. I would constantly get “the server is temporarily unenviable” error below.

This was a new migration so I first looked at all the CNAME and SRV records (internal/external), but they all seemed fine. Next we started looking at the firewall and went item by item until we found it.

The culprit was under Firewall –> App Control Advanced –> PROXY-ACCESS

The customer in question had set these to enabled. Once corrected Lync connected fine!