Hi,
so, this is how my Cable Modem is set up for IPv6:
The Gateway Address ((Link-Local) is populated
The Gateway Address(Global) is populated
The IPv6 Address Assignment is set to Stateless (Autoconfig)
And FromISP(Autoconfig) is also checked.
It's hard to judge your cable modem's IPv6 settings without more insight into the technical details of this device, which indeed operates as a router with an integrated cable modem. So if you tell us about IPv6 address assignments and gateways it is not clear if this refers to the WAN (cable) or LAN side of your router. But on the other hand it doesn't matter, because you seem to have perfect IPv6 access with any device that is directly connected to your router.
So do I select StaticIP or Stateless or Link-Local on the IPv6 Connection Type?
This depends on what you want to do with your DAP-1525. Whatever you select here should be irrelevant for the basic operation of this device, namely just stupidly bridging IPv4 or IPv6 packets from wired to wireless and vice versa.
This configuration item only refers to the IPv6 communication capabilities of the DAP-1525 itself (as a source or sink of IPv6 packets independent of its mere IPv6 passthrough bridging function for IPv6 packets not destined for or sent from itself):
- If you select Link-local Only (the default) the DAP-1525 is only able to talk to local devices via IPv6, e.g. you can reach the web interface from any local device within your LAN/WLAN via DAP-1525's link-local address (fe80:...), but DAP-1525 is not able to talk to the IPv6 Internet via IPv6
- If you want your DAP-1525 to be able to talk to the IPv6 Internet it needs a global IPv6 address. You can do this manually (by selecting Static IPv6) or automatically (by selecting Autoconfiguration (Stateless/DHCPv6)) which is recommended.
But all of that has nothing to do with your problem: Obviously your DAP-1525 has a problem with bridging IPv6 packets WLAN to LAN and/or vice versa. You can check if this is true by connecting one PC (call it PC1) directly to your router (cable modem) and another PC (call it PC2) to your DAP-1525. You could then measure network performance between PC1 and PC2 via IPv6 versus IPv4 (e.g. copying huge files between them from local disk to a remote network share and measuring the time it takes, and then calculating the network velocity [file size]/[time] or even more simple by looking at the network tab of the Windows Task Manager). You should see the same discrepancy between local IPv4 and IPv6 network velocity as you observed with IPv4 and IPv6 communication to the Internet, this way clearly having demonstrated that the DAP-1525 is responsible for this.
PT