Modem and router have same IP Address

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Occasional Visitor
I changed from Spectrum to CenturyLink. The Spectrum-supplied modem had an IP address of and my TP-Link AX1800 router has an IP address of
When I switched to CL, they gave me a Greenwave C4000 modem with an IP address of
The tech plugged it all in and the C4000 modem and the AX1800 router worked without any problems. To access the C4000 setup the takes me into the setup, no problem. The problem is I do not know how to access the AX1800 since it has(had) the same IP address as the C4000.
The connections are: Wan via DSL POTS line into the C4000. LAN#1 on the C4000 goes to the WAN port on the AX1800. A LAN port on the AX1800 goes into the desktop computer. The desktop has Win10 and does NOT have a wifi radio, only an ethernet port.


Senior Member
Disconnect the router from the modem. Log into the router and change the LAN > DHCP server range (to or something not in the same range), click save, wait for the UI and then change the LAN > LAN-IP IP address and save again (I believe that is the correct order; I haven't done it in a while).

Then reconnect the modem and you should be good to go.


Occasional Visitor
Thanks for the help. When I unplugged the CL modem, the AX1800 router is smart enough that it automatically changed from to
Not sure I understand how that worked, but it made my job much easier.
BTW, the CL tech had high praise for the AX1800 router. So far, for me, it has been a really solid router.

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