How can the default gateway of router change suddenly from 192.168.0.1 to 192.168.1.1?

Question

I used to access my home router—a TP-LINK model—at the address 192.168.0.1.

But today, I just couldn't do that. Apparantly, it the gateway got changed to 192.168.1.1 for absolutely no reason.

So, how did the gateway got changed? I knew that router generally used one of those IP’s by default. But, didn’t know that they could change the it just like that.

Could it my ISP or the manufacturer of the router or someone else? Also can manufacturer of the router push some sort of software update to the router? Does the router have some sort of operating system independently capable of doing that?

Edit: I found the DHCP settings of the router and it clearly showed that DHCP as enabled and "default gateway(optional)" was set to192.168.1.1. I tried to change it back to 192.168.0.1 to which I got:

Error code: 26106
The IP address is not in the same subnet with LAN IP address.

Answer 1

It could be one of the following:

1. Someone gained access to your router and changed the settings from inside of your network or from outside of your network. Your password could be too weak and thus allowed someone to get in by simply guessing it.

2. You (or someone else around) reset device to the factory default by accident.

3. Your device malfunctioned and reset itself to the factory default settings.

4. A vulnerability in your router could exist and someone used it to change configuration of your router.

5. Router's internal IP address is configured with DHCP and suddenly the DHCP configuration changed for some reason (it is possible, but very unlikely) - will depend on the exact model that you have.

Also can manufacturer of the router push some sort of software update to the router?

Usually firmware updates for devices like yours are published on the manufacturer's web site and users are responsible for downloading and installing them themselves. Thus it is very unlikely that manufacturer pushed some sort of update.

Does the router have some sort of operating system independently capable of doing that?

Yes, router does have some sort of operating system. And usually it should not change the settings without user interaction (unless configured to do so). But, still it could malfunction and change the settings.

Answer 2

I have the Tp-Link router model Tl-WR1043ND Ver 1.7 with the latest firmware .

I set the lan ip address of the router at 192.168.100.254 . The DHCP is set automatically at 192.168.100.100 to 192.168.100.199 . There are 10 computers with fix ip address . 192.168.100.1 to 192.168.100.10 .

Sometimes , the router ip address change itself to 192.168.0.1 . Maybe 6 times in 2 years . The DHCP became 192.168.0.100 to 192.168.0.199 . Now the router is not part of the local network . The router job is to connect everyone to internet . Now , nobody have internet . No emails ...

I do some maintenance on those computers from outside. There are 10 lines in the port forwarding section of the router . Those 10 lines are still there but became disable . The wifi part is OK

If I reset to factory default the router . All the configuration is lost and the router lan ip address became 192.168.1.1 not 192.168.0.1 .

I replace the router with the same model and same firmware . Same problem . At the beginning I had to go next to the router (100km away) to fix the problem . I found the remote management part in the router . Now I can fix that remotely .

The ISP is Videotron .

One cable modem connected to the router wan port . 16 ports ethernet switch connected the one lan port of the router . 10 computers and 3 network printers connected to the switch .

I don't know what to say . I thing it is a bug in the router ...

Rejean

Answer 3

Very simple answer, my cable router have address 192.168.0.1, you cant change that setting because provider lock router access. Automatically your wireless router adapt and change address to 192.168.1.1, and also your DHCP address range to 192.168.1.100 - 192.168.1.199. You are not hacked.
If you connect router on other network and factory reset it will change back to 192.168.0.1.

Answer 4

What address does your TP-LINK router have on its WAN port? Often the "modem" you get from your ISP is not just a bridging modem but actually a full gateway that does NAT and DHCP service. If that's the case for you, and if your ISP-provided modem (really gateway) started using the 192.168.0.0/24 subnet on its LAN side, your TP-LINK device would have had to switch to a different subnet on its LAN side in order to work.

When you were using PPPoE directly from the TP-LINK box, it was probably connecting to a PPPoE server at your ISP and getting a publicly routable IP address. When you switched to "Dynamic IP", it was probably relying on your ISP-provided modem/gateway to act as a NAT gateway and DHCP server. If that ISP-provided box was already using 192.168.0.0/24 as its NAT private (LAN side) subnet, then the TP-LINK box couldn't use it, so the TP-LINK box had to switch its NAT private (LAN side) subnet to something else, and picked 192.168.1.0/24.

That's assuming your TP-LINK box was smart enough to be helpful like that. Honestly I would have expected it to just fail and force you to fix the subnet conflict yourself.

By the way, if this hypothesis is correct, then you're effectively doing "double NAT" on your network, which is fraught with problems. I recommend everyone avoid double NAT unless you really really know what you're doing. Pick whether you want your ISP-provided box or your TP-LINK box to be your NAT gateway, and configure the other box to just transparently bridge traffic.