After a very painful installation process to get Proximus Ultra Fiber (8.5Gbps down/1.5Gbps up) I decided to remove the Proximus modem between my UDM-SE and the ONTP.
According to the Proximus documentation, for an FFTH installation this can be done by using VLAN 20 on the WAN port of the UDM-SE. We can configure this by navigating to Settings -> Internet -> Primary (WAN 1). Under advanced, we need to select Manual and check the box next to VLAN ID. We enter VLAN 20 as defined in the the documentation.
In the IPv4 Configuration part we select DHCPv4 and set the DNS Server to Auto as we’re using DNS Shield feature. In the IPv6 Configuration part we select SLAAC, configure the Prefix Delegation Size as 56 and set the DNS Server to Auto as we’re using DNS Shield feature.
Navigating to Settings -> Security we can configure the DNS Shield. I have it currently on Auto but you can also select static DNS over HTTPS providers by switching it to Manual. (due to a weird issue with YouTube history not being saved on mobile devices with the Ad Blocking feature, this feature is currently disabled for me.)
To configure IPv6 in your local VLAN, you can navigate to Settings -> Networks -> the VLAN you wish to modify. You select IPv6 and you can select Prefix Delegation and select Primary (WAN1) as the Prefix Delegation Interface. In the Advanced section, leave it on Auto and it should work now.
To allow IPv6 in the firewall. Create a new rule with the following settings: Type: Internet v6 In Name: Allow router advertisements Action: Accept Protocol: ICMPv6 and check Before Predefined Match Opposite: check
Now we verify if IPv6 works and looking at the below picture, this looks to be working fine.
