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Orbi RB50 assigning IPs out of range, wrong connect types
Anybody have any ideas? I've had years of no-hassle use from my Orbi system, but I'm at wit's end with current troubles. I have an RBR50 with satelites RBS50 and RBW30, connected to Comcast upstream...
jimslade wrote:i'll give the test a go. Now I'm super curious what else could be handing out IP addresses?? Cannot imagine what else has a DHCP server?!?
It is 99.999% certain that the Orbi is not assigning IP addresses that begin with anything besides 192.168.1.
So, either:
- devices are configured with static IP's that begin with 172, or
- some other DHCP server is giving out these addresses
You would probably remember assigning static IP's, so my money is on another DHCP server. Likely culprits include NAS servers and media devices. Some smart speaker systems attempt to network themselves.
I positively love capturing packets and looking at them with Wireshark, which puts me squarely in the uber nerd category.
Another simplistic question is, "what has been added to the network since things were fine?"
jimslade wrote:Main issue is my Orbi assigns out of range !P addresses in the 172. range. I've specified a range of 192.168.10-192.168-255, with some reserved IPs in the 192.168.1.2-9 range.
Is it correct to assume that the "1" was left out of the description of the DHCP range? i.e. the DHCP pool runs from 192.168.1.10 to 192.168.1.255?
I suspect that there is now another DHCP server on the network. DHCP is a really primitive protocol. Devices broadcast a request and respond to the first DHCP server that answers. (Seriously, the first. They do not 'wait and see' how many responses they get. First means first.)
An easy way to confirm (or deny) this hypothesis would be to temporarily stop having the Orbi act as a DHCP server, then turn off some device and power it back on again.
- If it gets an IP address, there is another server.
- The Orbi log file should not show a DHCP assignment (because the Orbi did not assign the IP address).
and there is another method that may detect another DHCP server on the network: Capture the WAN/LAN traffic and examine it with Wireshark. When a device is powered on, it will send a DHCP discover broadcast (to the MAC address FF:FF:FF:FF:FF:FF). The DHCP server will respond with a DHCP offer packet to the MAC address that the broadcast came from. This will contain the IP address of the DHCP server. Then, the device will respond with a request and finally an acknowledge from the server. This process is explained here:
https://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol#Operation
This should work as long as the two devices are not physically separated from the Orbi, such as on the same gigabit switch which has created tables showing which switch port every MAC address can be found on.