We have, for quite some time, had problems with systems on our LAN coming up "bottled," i.e., with non-functional connections. I recently noticed that the assigned IP addresses looked like they were colliding with fixed IP addresses on the LAN, which suggested that either the router/firewall (a TP-Link TL-WDR4300) wasn't honoring its DHCP range, or there was a rogue DHCP server in the network.
This morning, my iMac came up "bottled," and I was able to determine that the IP address had been vended by a DHCP server at the cable modem's address (192.168.0.1), even though the setup page for the cable modem shows DHCP as unchecked. Then, later, when I brought up my Chromebook (which almost always initially comes up "bottled"), I looked more closely at the address it had been assigned: it wasn't a collision with a fixed address (e.g., 192.168.1.102) at all; rather it was an address in the cable modem's range: 192.168.0.103.
This raises three questions:
- Why is the cable modem's DHCP server running when it's supposedly disabled?
- Why are addresses in the 192.168.0.x range "bad" on our network?
- What can I do about it?