【Typical Case】Users Cannot Obtain IPv6 Addresses After IPv6 Is Enabled on an RG-EW1200G-PRO

Keywords

IPv6, DHCPv6, RG-EW
Issue Description
An ISP serves as the DHCPv6 server, IPv6 is enabled on the RG-EW device, and DHCP is enabled on the WAN port to obtain IPv6 addresses.

The IPv6 prefix is configured on the LAN side and Stateless Address Auto configuration(SLAAC) is used to assign IP addresses.

However, clients connected to the RG-EW device cannot obtain IPv6 addresses.


Device Model and Firmware

Device Type	Device Model	Firmware Version
EW	RG-EW1200G-PRO	ReyeeOS  1.301.2324

Analysis Process

(1) Check the configurations and find that the IPv6 prefix on the LAN side conflicts with the IPv6 address of the WAN port.

However, a PC still cannot obtain an IP address after the LAN-side prefix is modified.
(2) Obtain packets on the RG-EW LAN port. The PC does not send RS packets, and SLAAC is configured on the RG-EW LAN side and uses RS/RA packets for interaction.

In addition, you can find that the PC sends a solicit packet. In this case, DHCPv6 instead of SLAAC is used on the LAN side. Therefore, it can be determined that the PC uses DHCPv6 to obtain IPv6 addresses.

After DHCPv6 is enabled on the LAN side, the PC can obtain an IPv6 address.

Note: The IPv6 address of the PC is assigned by DHCPv6 enabled on the LAN side of the RG-EW. To make this prefix globally reachable, the NAT66 function needs to be enabled on the WAN side to ensure normal Internet access.

(3) The PC can access the Internet properly using an assigned IPv6 address.

Solution

(1) Modify the IPv6 prefix on the LAN side to avoid conflict with the IPv6 address on the WAN port.
(2) Change the IPv6 address assignment mode to DHCPv6 and enable NAT66.