What activation error do you get in PhotoLab log, if any?
Did you use PL8 trial?
I had a different licensing problem after PL 7.5 → 7.6 update – connectivity was there, licensing worked, but PhotoLab log was polluted by hundreds of MB of activation errors. See PL7.6 (Win) ActivationCommon - Error while trying to get status: -6 . It does not match your case but checking PhotoLab log never hurts.
EDIT: What is the result of nslookup activation.dxo.com ? Note that ping may not work in your case because of ICMP filtering by your ISP and TCP is actually used (curl could be used, if you know it), so the ping test does not provide full connectivity info. In my case:
C:\>nslookup activation.dxo.com
Server: homerouter.cpe
Address: 192.168.8.1
Non-authoritative answer:
Name: activation.dxo.com
Address: 5.196.172.208
C:\>ping activation.dxo.com
Pinging activation.dxo.com [5.196.172.208] with 32 bytes of data:
Reply from 5.196.172.208: bytes=32 time=61ms TTL=114
Reply from 5.196.172.208: bytes=32 time=71ms TTL=114
Reply from 5.196.172.208: bytes=32 time=62ms TTL=114
Reply from 5.196.172.208: bytes=32 time=60ms TTL=114
Ping statistics for 5.196.172.208:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 60ms, Maximum = 71ms, Average = 63ms
C:\>