TPLINK WDR4300v1 DHCP issues [SOLVED]

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pacificstart
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PostPosted: Sat Nov 30, 2019 0:24    Post subject: TPLINK WDR4300v1 DHCP issues [SOLVED] Reply with quote
I upgraded to v3-r40559 and ever since the router (TPLINK WDR4300v1) seems to forward the DHCP requests from the LAN /WLAN to the WAN port and also forwards DHCP replies coming from the WAN back to the LAN/WLAN.

The router is set up in gateway mode and has DHCP server enabled and authoritative with range > 192.168.1.100

The WAN port is connected to a cable modem which has a built in DHCP server that I cannot disable as I have no control over it. The cablemodem assigns IP addresses in the 192.168.100.x range and as a result some (not all and not all the time) of the LAN/WLAN clients end up with an 192.168.100.x address instead of 192.168.1.x.

If I assign IP manually to the clients they seem to work fine.

It looks like the router is acting as a DHCP forwarder but it's not supposed to.

Is there a way to prevent that?
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kernel-panic69
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Location: Texas, USA

PostPosted: Sat Nov 30, 2019 1:00    Post subject: Reply with quote
Does it say "DHCP server" or "DHCP forwarder" on the main setup tab under Network Setup ?
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pacificstart
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PostPosted: Sat Nov 30, 2019 2:49    Post subject: Reply with quote
It says DHCP Server.
kernel-panic69
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PostPosted: Sat Nov 30, 2019 4:46    Post subject: Reply with quote
Ok. Here's the thing. If your modem is handing out 192.168.100.x IP addresses, if it's in bridge mode, then it's not recognizing your router, sounds like. Does your router have date and time showing? Now, if your modem isn't in bridge mode, then that's a different problem, but if it is, it sounds like it's looking for a specific mac address to connect to it. Outside of that, the only thing I can suggest, IF your router is connecting to the internet and can ping and lookup internet addresses fine from CLI via ssh/telnet, is to check 'nvram show | grep dchpfwd_enable'. If it's '1', you need to do a 'nvram set dhcpfwd_enable=0 && nvram commit && reboot'... but I have to ask, is dnsmasq enabled? If not and if it's not running, then I think that may be your problem, but this is the first time I have heard of this kind of behavior....
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pacificstart
DD-WRT Novice


Joined: 08 Mar 2007
Posts: 6

PostPosted: Mon Dec 02, 2019 23:24    Post subject: Reply with quote
I just checked nvram and dhcpfwd_enable=0.
Also dnsmasq is enabled.

The router is connecting to the internet and all the fixed IP addresses have no issues connecting.
Some of the dynamic IP addresses seem to be assigned ok as well, it is mind boggling, I am out of shots here....Sad
pacificstart
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Joined: 08 Mar 2007
Posts: 6

PostPosted: Mon Dec 23, 2019 2:31    Post subject: Reply with quote
Issue solved: I have switched providers and got a new modem about a year ago but I had the old one still on an plugged in to the main switch and didn't realize it until now. The old modem was giving 1 min leases all this time and some clients were getting them and some weren't (:
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kernel-panic69
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Joined: 08 May 2018
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Location: Texas, USA

PostPosted: Mon Dec 23, 2019 4:13    Post subject: Reply with quote
d'OH. Glad you figured it out.
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