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Report on good VDSL2 experience with Zyxel XMG3927-B50A

1 of 7

Hello everyone!


Luca here, with a report on the good experience I am having since this morning, as I swapped my old Internex-Box 2 replacing it with a brand new Zyxel XMG3927-B50A.


I have enough experience with networking, TCP/IP and configuration of devices, and I wanted a device which would support VLAN, something the Internet-Box 3 doesn't do, so I decided to go the 3rd party way and got the Zyxel.


The setup was quite fast, and the DHCP option 60 was the only thing that needed to be activated on the WAN/VDSL2 port. The content was already populated, so I simply needed to check the box:




The connection to the VDSL2 network I have here worked immediately, and I have a full 120M down and 40M up, which is slightly faster than what I had with the IB2.


The other issue I had was that of IPv6 support. The default setting for the 6rd tunnel configuration taken from DHCPC did not work, and browsing the internet here and there I found some very interesting documents related to 6RD and the way Swisscom uses it, which was a good technical reading which helped me to find the correct parameters to manually configure 6RD.


In order to do so, I had to change the "IPv4/IPv6 Dual Stack“ which is the default setting to “IPv4 Only“:




Changing this setting allows the 6RD configuration to show up on the right side of the configuration panel, and the correct configuration parameters are those shown here:




6RD needs the Border Relay IPv4 Address in order to work, and the current configuration for the Swisscom network is


The IPv4 Mask Length is 0, which means that the whole IPv4 address (32 bits) is mapped in the IPv6 address.


The Service Provider IPv6 Prefix is used as the main supernet in which 6RD maps the IPv4 32 bits plus the local interface addresses.


More information on IPv6, 6RD and some details of the Swisscom configuration can be found in these great articles:


Hopefully these information can be useful to others.


So far the experience with the Zxyel XMG3927-B50A is excellent.


Any questions or comment, feel free to write!


Ciao a tutti!



6 Comments 6
Black Mamba
2 of 7



Thank you for this experience sharing 😀

3 of 7

That's the way.

Thanks Luca
Falls du in deinem Thread eine Antwort von Tux0ne wünschst, so ergänze deinen Text mit @Tux0ne. Damit erhalte ich eine Benachrichtigung.
4 of 7

Thanks to you @Tux0ne for providing good insights on the 6RD configuration.


In spite of my little knowledge of German, your article proved quite helpful, and so I decided to share my experience with others so they could use this as a reference, hopefully!


Vielen Dank!



5 of 7

Hi Luca,


I have an IB (internet box),  I think it is the first version.  I've spent hours trying to get pfsense (2.4.5p-1) installed between the IB and my local LAN.  Everything works except this damn Multicast that forces the TV to freeze every 4-5 mins now.  


My setup is    Internet <-> IB  <-> pfsense (dual card WAN/LAN 10 GB) <-> Netgear XS708T <-> Netgear GS108TV3 <-> TV box.  For testing purposes I put the pfsense just between the TV and the WAN connection taken from the GS108TV3 - though still the freezing problem after 4-5 mins.  The TV signal restarts by changing channels,  it's like there is something missing to tell it everything is still alive.


I've configured the 2x switches and pfsense box as indicated by Tuxone - the network works fine with the IGMP snooping setup on the switches (without the pfsense).      Though once pfsense is connected,  I have problems with the TV.   You weren't clear in your post as to whether you have pfsense as part of your setup?


I read somewhere that the double NAT may be problematic.  Hence why I think of following your solution and removing the IB and having a Bridge (with the Zyxel).  There was also mention somewhere of having the IB in DMZ mode pointing towards the pfsense server.


I also read somewhere that because there are 2x switches on the network,  that the "Querier" function should be setup for Snooping.  I'm not sure if a VLAN is required to force all traffic to the correct destination.  I read somewhere that it is not essential if operating on VDSL2.


Any hints, ideas or suggestions welcome!    




Black Mamba
6 of 7



I don't know if you want to do that to yourself until pfsense can be configured.

But basically. If the Netgear router is in bridge mode, you have to configure everything on the USG.

For the WAN, the VLAN ID 10, DHCP as well as the DHCP option 60 (100008,0001)

For Swisscom blue TV, igmp snooping alone is not enough, you also need an igmp proxy.

You can find the config in this thread:

Gelöst: Swisscombox Plus nur als Modem vor Ubiquiti USG be... | Swisscom Community​

7 of 7

Thanks Black Mamba,


I think I've narrowed it down a bit better,  it doesn't look to be a problem with pfsense,  I tried updating to 2.5 though it didn't make any difference.  I even mucked around with PIMP (a supposed replacement for IMGP) 


A clue seems to be with the switch (I have 2x on the network - Netgear XS708T and GS108Tv3).  As the Swisscom TV freezes after working for approximately 4 mins,  it looks to be related to some sort of "time-out".  The setting on the switches is 260 seconds for the IGMP host timeout,  this corresponds closely to the time that the channel freezes on Swisscom TV.


I followed TuxOne's configuration,  though I don't see anything about IGMP Snooping Querier.  I found the following on this website below (I haven't had time to try it out - TV is blocked from use which creates a problem with wife & kids :)):

Option 1: Increase the Group Timeout value to a large duration or set it to never timeout. This will prevent the switch from clearing out the port list information and hence will not block multicast messages.


Option 2: Use IGMP Snooping Querier. The IGMP Snooping Querier is available in popular switches which support IGMP snooping. This Querier mimics a multicast router by sending out IGMP Query messages to the hosts and the Membership Report messages from the host allows the switch to refresh the port list information preventing the Snooping Group Timeout from occurring.


If anyone has a configuration that works and resolves this problem,  then any help or suggestions are welcome!





PS good advice Black Mamba,   one problem at a time.  Forces a methodical approach based on understanding 🙂

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