Well shack, this is when I have sympathy for those people on the end of a support line.
Idle googling suggests (and it's a guess) that you have a FreeBox HD set top box connecting you to the internet. Well, another guess is that this is a proprietory type solution. The manual is here and it's a PDF and in French.
ftp://ftp.free.fr/pub/support/MANUEL...-BOITIER-A.pdf
Section 4.5.4 says you can mess with the ping but you need to login to the box.
Basically all I would suggest is connect via a cable and not WIFI. Reboot your box (how to do that is in the manual, in French) and reboot your PC. Lame eh? Then type
ipconfig /renew
in your DOS shell.
If that doesn't work then prepare to pay 34c per minute to speak to support line which I am sure is happier to speak in French than English.