Hi 175n,
Information: I disabled IPV6 on routeur, results of my tests:
1st try: Ethernet connected from the switch to Formuler Z8
- after first start , only connected on wifi , ethernet is still "not connected"
- I used the "restart" feature available in the menu "Power", but i'm still always connected only via wifi with ethernet not connected, i tried 3 times...
- I used the "Power off" feature available in the menu "Power", restart the formuler Z8 using the remote, Ethernet is now connected and everything is ok.
On each tests, my IPTV worked fine with VPN activated
2nd try: I just removed power cable of the formuler Z8 and connected it to the sagem routeur directly, idea is to be as the same status of the first try
- after first start , only connected on wifi , ethernet is still "not connected"
- I used the "restart" feature available in the menu "Power", but i'm still always connected only via wifi with ethernet not connected, i tried 3 times...
- I used the "Power off" feature available in the menu "Power", restart the formuler Z8 using the remote, but Ethernet is still on "Not connected"
After lots of tests, I decided to connect it like it was when i setup it, and ethernet was connected !?!?
The formuler is connected via:
Sagem BOX -> Switch 3com -> to switch dlink POE -> Formuler Z8
As I said, it connects randomly, If i could have access on the logs , it should be fine to understand what's wrong 
Thanks for your help,
Regards,
Jerome
sorry for my english, it's not my native language ;p