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Forum Discussion
Wrong IPs being given out
I have a SXR80 modem as well as a SXS80 satellite mesh system. Everything was working fine until a slight power outage happened and all of my IoT devices restarted. Of my 30 light switches, 3 conne...
Yes, the router sits behind a modem that has had its DHCP turned off, and its WIFI turned off.
The different LAN settings are such:
LAN1 is 192.168.0.xxx. DHCP Range of 192.168.0.21 - 253
LAN2 is 192.168.20.xxx. DHCP Range of 192.168.20.2 - 254
LAN3 is 192.168.30.xxx. DHCP Range of 192.168.30.120 - 254
LAN4 is 192.168.40.xxx. DHCP Range of 192.168.40.2 - 254
Last time the problem I had was nothing was being picked up at all. All of my devices refused to connect to the network. I shut everything down for an hour (it was like little house on the prairie around here!). After the hour I turned on the modem and waited 10 minutes. Then the router/satellite, waited 10 minutes. Then each computer, waited 10 minutes. Then one by one turning on or restarting each IoT device until everything was online. Took about 3 - 4 hours in total. That's when the suggestion of setting static IPs for everything came up.
This time, things are being seen, but a lot of the IoT devices are being picked up on that 192.168.1.80 IP address. I will try your suggestion tonight after everyone has gone to bed since the computers and TVs are connecting without a problem.
Thank you.
tehBob wrote:
Yes, the router sits behind a modem that has had its DHCP turned off, and its WIFI turned off.
One thing to keep in mind is that a device which features DHCP and WiFi is a combination modem/router/wifi (the sort of device that ISPs almost always want to install because that leaves the customer with a fully functioning connection without requiring any equipment from the customer.
This can create a "Double NAT" situation which can result in specific applications not working correctly. Things like forwarding internet ports to internal servers, providing VPN access to the LAN from the internet, and certain types of internet gaming. The net is rife with explanations of Double NAT, including this one from Netgear:
https://kb.netgear.com/30186/What-is-Double-NAT
As long as this does not affect you, then there is no reason to take any action.
Or, perhaps the ISP device has been put into "bridge" or "passthrough" mode?
tehBob wrote:
The different LAN settings are such:
LAN1 is 192.168.0.xxx. DHCP Range of 192.168.0.21 - 253.
The User Manual states on page 121 that the default IP subnet for LAN1 is 192.168.1.x.
https://www.downloads.netgear.com/files/GDC/SXK80/Orbi_Pro_WiFi_6_UM_EN.pdf
My guess is that the LAN1 setting was changed was:
- You just like this setting?
- because the ISP router assigned an IP address beginning with 192.168.1.x to the Orbi WAN port and the Orbi changed the default setting to this, rather than 192.168.1.x? If this is indeed the case, then the ISP router may actually be assigning DHCP addresses in the 192.168.1.x range
Modem is set to pass though mode.
I changed the default IP range of LAN1. My fingers are use to typing 192.168.0.xxx for so many things, just made life easier for me (until now).
Even if the AT&T modem was sending DHCP addresses out, that wouldn't explain why there are 30+ devices with a 192.168.1.80 IP address. All devices have different MAC addresses so the DHCP server wouldn't be able to set another device with the same IP. I double checked the AT&T modem for DHCP leases. Currently 0 DHCP leases.
As a side note, is there anyway to force removal/DHCP lease renewal? I see a way to block devices once connected, but no way to force them to renew their lease.
Thanks for explanation. Makes perfect sense.
What does not make sense, of course, is how this could have happened in the first place. There is no DHCP server assigning IPs in the 192.168.1.x subnet, yet all these devices are connected to the Orbi and claiming to be 192.168.1.80. The Orbi process which populates the Attached Devices table may be a bit "brain dead." i.e. "This device says it is 192.168.1.1, so that's what I put into the table."
Being a bit of a computer nerd, I would probably set up Wireshark to capture the Ethernet port on a computer attached to the Orbi, open a command window, and attempt to ping 192.168.1.80. This should cause the computer to issue an ARP command to discover which MAC address has 192.168.1.80 and Wireshark should capture all of those devices responding, "This is my IP address"
tehBob wrote:
As a side note, is there anyway to force removal/DHCP lease renewal? I see a way to block devices once connected, but no way to force them to renew their lease.
Really good question. I see that this question has come up before:
https://serverfault.com/questions/285048/dhcp-server-tell-clients-to-renew-lease That would almost certainly work with devices connected directly via Ethernet. WiFi is a bit different. My guess is that disabling the WiFi SSID would cause devices which are connected to sense that the connection has 'gone away' and go into discovery mode. When the SSID reappears, the device might go through the typical sequence:
- Probe Request.
- Prove Response.
- Authentication Request.
- Authenticaion Response.
- Association Request.
- Association Response.
- DHCP Request.
- DHCP Response.
The only way to validate this hypothesis would be to disable, then re-enable the IoT network (SSID).
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