I am using the TP-Link C7 modem and recently updated to the latest firmware 180114.  It works fine otherwise.  It appears I can ping the other devices on the local net with their IPv6 addresses.  However, I cannot ping the other sites' IPv6 addresses on the internet.  As most of the latest operation systems are default to IPv6, I cannot even ping the site like google.com.  I can only do that be change my PC's operation system to default to IPv4.  I am just wondering if this is because my C7 router?  It appears that C7 has some IPv6 setting but I cannot make it works with IPv6.  Has anybody encountered the same problem in the past, or I will need to get a newer router?  Thanks in advance for your help.