Hi,
I am new to Matter. I installed Matter server and added my first WiFi device sucefully. I manage my internal device, with Fixed IP address, to avoid any issue if my DHCP server on the router fail, so I would like to add a fixed IPv4 address on my matter devices. For now is a Nous Plug https://nous.technology/product/a8m.html?show=manual
Thanks in advance for any suggestion
Marco
Hi,
Matter uses IPv6 and mDNS for device discovery so a dynamic IPv4 doesn’t make a difference. Matter is IPv6 based but has some recommendations for dual-stacking with IPv4 but ISTR that’s more for border routers connecting over a WAN rather than LAN.
Should your DHCP server die, the devices will continue with the existing IPv4 leases until (depends on config) 1/4 or 1/2 the lease time when they ask for a lease extension. On my own network I’ve only noticed a dead DHCP server (AdGuard issues) when IPv4 only devices started being uncontactable. Most just worked using IPv6 - which made troubleshooting weird until I realised what was going on.
Personally I’d set HA with a static IPv4 address (for easier admin), and that’s it.
I’d not bother attempting to set a controlled device to a static IPv4 - and I’m not sure it is possible.
If this helps, 
this post!
Hi @FloatingBoater,
I just have HA with static IPv4 address, but I have IPv& disabled on HA. So It is better to enable it?
Thanks
Matter uses IPv6, so if you want to use HA with Matter, enable IPv6:
Very strange, only matter device I have work with IPv6 Disabled on HA, perhaps it fall back on IPv4 in this case.
I enable IPv6 on HA.
Thanks
Marco
I have heard others say they have IPv6 disabled on HA, yet they have Matter WiFi devices added successfully. If you would be so kind, goto UI->Settings->Devices&Services, select Device tab, find your Matter WiFi device, and click on it. Then click on “Device info”. Does it show an IPv6 address?
They will actually continue until the lease time expire.
The 1/2 time re-lease request is just to act out due diligence and avoid last minute chaos, if a drop out occur.
IPv6 is autoconfiguring itself without the need for a server.
Another thing that would be good to know is to check your HA’s IP addresses at the HAOS level.
If you have time, also go into your HA’s machine console, or SSH to get a command line prompt
and enter
ip addr
to see what addresses your HA’s Ethernet interface has.
If too much information scrolls past your screen, you can probably get the same using: ip addr | grep "2: e" -A7
Thanks for that 
It does indeed show that HA has an IPv6 address (its a link-local address), which most likely explains how/why your WiFi device was successfully added to a Matter Server even though your HA UI says that IPv6 is disabled.
To me this means that if your Router were to fail and the Device’s IPv4 lease expired, then it would continue to communicate with your HA Matter server using IPv6 as intended.
I added Matter device succefully before enable ipv6🤔
Hmm… then I would suggest running another experiment by disabling IPv6 in the UI, then reboot HA just to make sure it picked up the change, then check again with the command line prompt to see if there is an IPv6 address or not. I only suggest this, because I have seen from other users who have said that they disabled IPv6 in the UI but they found they still had IPv6 address(es).
No, it will use IPv6 all the time.
IPv6 is in the TCP/IP standard set to default take precedence over IPv4.
That’s what I said
I will test on my test HA installation and I’ll be back
Thanks
Hi,
here is network config on my test box, with IPv& disabled
IPv6 is still present but say method: disabled
I am pretty confused😒
OK, so you’ve confirmed that you still have an IPv6 address (link-local) and explains how you were able to commission and use the Matter/WiFi device even though the UI had IPv6 disabled.
Yes I understand why. After digging around some more, it appears that there are some other hidden configurations under the HAOS Linux side of things that keep the IPv6 stack running.
So back to your original posting, you should still not have any issues since Matter will use IPv6 regardless of the device’s IPv4 lease time expiring and your HA will still have IPv6 running even though the UI may have IPv6 set to disabled.
The control in HA Settings → System → Networks → IPv6 → Disabled actually disables some IPv6 addresses, but does not appear to disable the whole IPv6 interface, allowing one type of IPv6 addressing to still work.
This is how Matter (which is IPv6) worked with HA IPv6 disabled.
There are several types of IPv6 addressing as the network is a lot more self-configuring than IPv4 can be (e.g. some local IPv6 modes do not need DHCP nor DNS vis SLAAC).
I’d suggest Wikpedia or the Matter CSA for more reading.
I think the IPv6 settings in HA only disables IPv6 on that container.
The Matter server is another container and that does not get disabled.
