As many users in here I have a pretty high number of cameras and other smart devices, and especially for NAS support and recording making it possible to assign a fixed IP adress for the cameras would be HIGHLY appreciated, because everyone that experience a router reboot or WiFi reboot the Aqara cameras tent to change IP adress making the NAS surveillance disconnect the cameras.
So @AqaraOfficial PLEASE make it possible to assign fixed IP adress for each camera. 
What is the brand of your WiFi router/access point? You can probably set static address in the router settings, while static IP address in camera settings may break connectivity (what if the IP address is rejected? You have to re-pair the camera because it’s disconnected from the WiFi and you cannot change the IP settings now)
It’s far better to set static IP addresses at the router level. If a fixed IP address is set on an end device and not on the router, and that device goes offline for a while, the router may assign that IP address to another device, and when the device comes back online there’ll be an IP address conflict and it won’t be able to connect again. With it set on the router it’s reserved only for that particular device and will only ever and always be assigned just to that device.
Just set it on my switch but have seen that fail from time to time as well (UniFi) but in general what I have set fixed IP on the end devices (all of them) it works like a charm. Might just be me but would prefer to have the solution available.
My router is my ISP providers and ot really suck, but have set it in my UniFi switch instead but have seen that create problems from time to time.
My ISP (Orange) allows me to set static IP addresses, check the sticker on the router if you have password and IP address of the router’s settings. It should have more options that whatever’s provided in the user friendly app of your ISP.
Alternatively you can just enter the gateway address into the browser to check if you can access the router settings.
Personally I have made my network ISP-agnostic, I have setup my own router (with mesh wifi) connected via Ethernet to the router by the ISP. This way, if I changed the ISP, then my network setup will stay the same. All my devices connect to the network created by my TP-Link Decos and don’t know anything about the ISP’s network.
And I strongly recommend you to do the same if you have network devices like NAS and cameras. If your network setup is very much attached to the subnet of your ISP, it will be a headache to setup it once again if you start having problems with your ISP or your ISP replaces your model/router.
My ISP replaced 2 years ago because they decided their old router is too old to handle my new internet plan. I can’t imagine how much work it would be for me if not for my network setup.
I have considered going that route too, but as I have fail over router (5G Mobil router) I would need to double everything configuration wise, why I have used my switch for that as both my 5G router and fiber router are connected to the switch, but if the end devices all have fixed IP’s that should in theory be easier, but guess time will tell.
Hmm, but I don’t see how that would mean that you double everything.
You setup your own router with your own subnet. All devices connect to this network and you have one route called WAN that, normally, connects to your ISP’s router. Just separate your network from the “internet source”, whether it’s the ISP or the 5G modem.
You said you use UniFi devices. Those gateways/routers actually support WAN failover setup. Which means you can configure your network to use the interface connected to your ISP’s router as primary WAN, and another interface connected to the 5G modem as failover.
Hello, I regularly set a permanent IP for all smart home equipment connected via WiFi. This allows me to quickly monitor the status of the equipment.
I would never use an IP address dynamically assigned by the DHCP server as a static address. Simply assign the DHCP server a start address like 192.168.0.11 and an end address like 192.168.0.99; then you can use the lower and upper address ranges for static assignments to devices. This completely prevents any IP conflicts caused by the DHCP server.
You can also run a separate DHCP server on the network and simply disable the DHCP in the router. If you already have a server or NAS on your network anyway, you can just install a DHCP server there. Most of the time, these standalone solutions are even easier and more comprehensive to configure, such as binding a MAC address to an IP.
Absolutely right. For IPv6, by the way, I would fundamentally rely on SLAAC (Stateless Address Autoconfiguration) and set a Unique Local Address (ULA) starting with the fdxx:: prefix in the router, and definitely not a Global Unicast Address (GUA) starting with 2xxx:: from the ISP. This is especially true if you don’t have a connection with a fixed IP, because if the prefix changes, your Matter devices will otherwise go offline.
Whether you also need a DHCPv6 server is something everyone has to decide for themselves. Personally, I don’t really want to deal with it.
SLAAC vs DHCPv6: Choosing the Right IPv6 Address Assignment
You can fix this issue in the router by making “DHCP Reservations”. Basically, you tell the routers to ALWAYS assign the same IP to the same MAC address. Every router I have seen allows this. Many have a limit like 50 reservations max. But that’s enough. Almost certainly, your router can do this.
You are correct the it is best done at the router. Central managment of IPs is good. But you example if a colision is just a case of setting it up wrong. A common stanadrd way is to tell the touters the the pool of available dynamic IPs start with 100 and goes to 250. then if a device MUST have a static IP you can remeber to alway use IPs lower then 100. There is nothing magic about “100” except that isit easy to remeber and is common industry practice.
I set up my network exactly as @JohnD described. Static IP addresses hasn’t changed since day one. So this works pretty well here on my end. Using Unifi as well