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9 Messages

Thursday, October 17th, 2019 11:00 AM

IPV6 Setup 3939B and Unifi USG

Attempting to setup IPV6 on a Unifi USG 4Pro version 5.11.50. I have a 3939B from Comcast, and I have been told it's the most up to date modem adn should route IPv6 to my firewall. I have a static IPV4 block and static IPV6. I'm trying to set the USG as a static IP.


For my WAN setup I'm asked for the following:

IPV6 Address - I'm using the IPV6 address located on my account page.

Prefix Length - Based on Comcast help documentation, I believe it's 64 even though my account page shows 56.

Router - I'm currently populating the field with the WAN IP Address from the modem WAN Status webpagebut there are other fields that might be right: WAN Default Gateway address fe80::b290:xxx and a delagated prefix which is the same address that shows on my account page. I'm currently populating the field with the WAN IP Address. There's also a WAN link local address.


For my LAN setup I'm asked for the following

IPv6 Gateway/Subnet - what data should go here? Is this my delegated prefix? Based on what I enter, the webpage for the USG/Unifi prepopulates a DHCP6 range. And I'm told hte lease range has been limited to 2000 leases.


I would really appreicate any help.




261 Messages

5 years ago

Hi there JeffreyWest! The usual prefix is a /64 even though the gateway is typically assigned a /56. Comcast Business IP Gateway and Static IP overview has really good information. Have you already disabled the firewall and DHCP (to configure your own static routing) on the 3939? That gateway will allow you to enable passthrough mode and Comcast_John gave a really good overview of the differences between that and true bridge mode in the forum thread ''True Bridge Mode’ vs. 'Pass-Through Mode' . Let us know if that helps and if you need any other support!