@YugeSupport 

Other that the size of the subnet there is no difference between an Class B private IP andress 172.16.x.x and a Class C IP address 192.168.x.x, especially if you are using DHCP to assign your devices IP addresses.  The Change of IP can be related to the ISP and how their service or equipment is setup.  Is your service modem also a gateway?  If its a gateway is this device configured as a modem only or as both a modem and a router.  If both what is the LAN Address being broadcasted?  

@Carl hey there, I just came across this random changeover as well. The default up range I had for my deco M9+ setup was 192.168.68.x and changed it over a few months ago to 192.168.1.x. as of this morning, however, it changed to 172.16.0.x and I now also can't change the IP address of my network at all wherein the app is telling me to try again later.

I have my own modem which doesn't have a way to change the addresses. The decos are setup as a gateway. 

@haithcockce 

Can you provide the following:

Deco hardware version

Deco Software version

Deco app version

Device its being used on.  iOS or Android.

@Carl 

I am having the same issue. Switching from 192.168.0.x to 172.16.0.x randomly. After a full system reboot(modem, router), it sometimes fixes itself. We once watched the DHCP settings change right in the app without us even touching a thing. The numbers just changed. This is annoying as we have devices with static IPs that get messed up when the whole range of the network changes. Is there a fix for this? It seems to be happening to other people as well.

We have these network devices:

Spectrum DOCSIS 3.1 Modem / Voice Combo (Model: Ubee EU2251)

Tp-Link Deco M3W system with firmware version 1.4.3 Build 20200918 Rel. 74289

Android Phone App Version 2.3.2

@Terps 

Thanks i have sent this up to development to investigate 

@Carl I have exactly the same issue.

Last 2 times I rebooted my Router node -- both times my network went from 192.168.1.1 to 172.16.0.1.

One unique thing about my setup is that I run my own DNS Server, and I have my (Advanced > IPv4 > Internet Connection Type > Obtain DNS Automatically (off) )Primary DNS setting set to 192.168.1.10 for that reason.

Additionally, I have a static address reservation for 192.168.1.10 as well -- to ensure my DNS server can get the same IP everytime.

Hi Everyone so I have some information. 

Deco will automatically change the DHCP settings on your LAN if a conflict is detected. 

Case 1. If a customer changes the LAN IP address to a value that is conflict with the WAN interface, then the app will remind that it's an invalid address and cannot be saved.

Case 2. If a customer changes the DNS Server on the WAN interface to a value that is conflict with the LAN IP address, the app won't give a remind but will change its LAN IP address automatically to another subnet to avoid the conflict.

Case 3. If the the DNS server on the WAN interface changes automatically due to a DHCP renew, the app will perform like case 2.

Basically changes should only happen is the subnet comes into conflict with that being used by the WAN.  This should only happen if you are in a double NAT environment.  The recommendation is to put your gateway in Bridge mode or put the Deco in AP mode and let the Gateway handle the DHCP.  However if both devices are routing and providing private IP network this is a possiblity, even if you set your own DHCP on the Deco.  

@Carl 

Case 2. If a customer changes the DNS Server on the WAN interface to a value that is conflict with the LAN IP address, the app won't give a remind but will change its LAN IP address automatically to another subnet to avoid the conflict.

 

Looks like I am running into case 2. I verified by removing my DNS server from WAN DNS settings and rebooted all mesh devices.

Let me explain my use-case of why I put the DNS server in WAN settings in the first place.

I want to direct devices on my guest network to use my DNS server.

1. Out of the box, if I configure DHCP settings to provide my local DNS server, the Guest devices cannot reach it. This is understandable since Guest network is supposed to block out all requests to other devices on the network.
2. In order to do a workaround, I configure my DHCP settings to provide 2 DNS server addresses 192.168.1.10 (my dns server), and 192.168.1.1 (tplink router address)
3. Additionally, I replace WAN DNS to point to 192.168.1.10.
4. This enables a device on Guest network to reach out to my DNS server.

Is there a different way I can get my guest devices to use my DNS server?

@U_S 

I asked about this too and when using a private DHCP server the Deco would need to be put in AP mode.  Here is the explanation why.

As for the case that providing DHCP from a private server, Deco must be set up in AP mode and it will work as expected. In Router mode, Deco doesn't have an option to disable its own DHCP server. And in case the customer set up a private DHCP server under the Deco network, then there will be two DHCP servers in the network and some clients obtaining IP address from the private DHCP server won't have internet access.