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D6200 Wireless assigning wrong IP address to DHCP clients

MondoTV
Aspirant

D6200 Wireless assigning wrong IP address to DHCP clients

Ok this is weird one - I have two internet connections through two different providers (because one is so bad we had to get a second).

Both are ADSL on Netgear wireless routers. One is a Telstra  Smart business modem router V7610 and that is set to the address range 192.168.0.0. The other is a D6200 using the address range 192.168.10.0. Both are using DHCP set to their respective address ranges - the V7610 is set to the full address range 192.168.0.2 - 254, the D6200 to 192.168.10.150 - 199.

However when wireless clients connect to the D6200 they are using the 192.168.0.0 address pool - for example my mobile is currently connected to 192.168.0.21 even though it is connected to the D6200. I've attached screenshots of the setup..

The wired LAN works as expected but I think I've manually applied all the IPs on that. If I try to manually apply an IP in the correct address range to the D6200 wireless connection it gets a no internet available. eg 

IP: 192.168.10.101

Subnet mask: 255.255.255.0

Router: 192.168.10.1

does not provide an internet connection.

 

192.168.10.1

Model: D6200|Dual Band 11ac ADSL Modem Router
Message 1 of 8

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antinode
Guru

Re: D6200 Wireless assigning wrong IP address to DHCP clients

> [...] I actually have three routers [...]

   "switch" and "router" are spelled differently for a reason.

> [...] (apart from the modems) [...]

   Among the "modems" are you counting modem+routers like the D6200?
The router part of modem+router may be more important in this situation
than the modem part.

> 2. TP Link T1700X-16TS is a 12-16 port 10gig E router [...]

   According to TP-Link, it's a switch with some router capability.

 

      https://www.tp-link.com/uk/products/details/cat-40_T1700X-16TS.html

What you're doing with it is not entirely clear.

3. TP Link TL-SG1016 which is a 16 gigabit router [...]

   According to TP-Link, that's a switch, not a router.

 

      https://www.tp-link.com/us/products/details/cat-42_TL-SG1016.html

> [...] The D6200 is connected to this router which sits on the
> 192.168.10.0 subnet.

> Both gigabit routers are connected to the 10GigE router.  But not
> directly to each other. [...]

> [...] (Hint: If a device has multiple Ethernet ports, then "connected
> to device" is not enough detail.)

   Still true.  "But not directly" wouldn't save you.  A network switch
is very permeable; that's its whole reason for being.

   That description is too vague for me to understand what is actually
connected to what.

> [...] Some of the computers on the network are connected to all three
> (single cable -multiple IP addresses) [...]

   You lost me.  How does one computer interface get "multiple IP
addresses"?

   Between your network configuration and my feeble mind, at least one
of us is confused.

   Based mostly on speculation, my current guess is that you have
connected the LAN sides of the two modem+router devices together
physically, even though they use different LAN subnets.  One potential
problem with such an arrangement would be that when a client device
broadcasts a DHCP request, it could be received by the DHCP servers in
both (modem+)routers, and the client device would take its IP
configuration from the first DHCP server to respond.  Thus, a client
device might get a "192.168.0.x" address from (the DHCP server in) the
Telstra modem+router, or it might get a "192.168.10.y" address from (the
DHCP server in) the D6200 modem+router, depending on which gizmo has
more idle time at the moment.

> [...] I have two internet connections through two different providers
> (because one is so bad we had to get a second). [...]

   That might have been harmless if you had kept the two LAN segments
separate, but I suspect that you've connected them, and thus created one
unholy mess.  I wouldn't guarantee that it couldn't possibly be made to
work, but, as I said, running multiple, independent DHCP servers on one
LAN segment would be begging for trouble.  (Plenty of which you seem to
have acquired/generated.)

View solution in original post

Message 7 of 8

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antinode
Guru

Re: D6200 Wireless assigning wrong IP address to DHCP clients

> [...] I have two internet connections through two different providers
> (because one is so bad we had to get a second). [...]

   Did you connect the two routers to each other?

Message 2 of 8
MondoTV
Aspirant

Re: D6200 Wireless assigning wrong IP address to DHCP clients

Yes - via a router

Message 3 of 8
antinode
Guru

Re: D6200 Wireless assigning wrong IP address to DHCP clients

> Yes - via a router

   That tells me approximately nothing.  _Another_ router?  An accurate,
complete equipment inventory might be a good way to begin.  What,
exactly, is connected to what, exactly?  (Hint: If a device has multiple
Ethernet ports, then "connected to device" is not enough detail.)

Message 4 of 8
MondoTV
Aspirant

Re: D6200 Wireless assigning wrong IP address to DHCP clients

Fair enough. It is quite a complicated system though. Before we do that (because it will take me a while) I havemanaged to establish some more facts. I set my phone to manually access the router in the 192.168.10.0 range. This resulted in a successful connection to the router but no internet connection. So I went back to DHCP and lo and behold this time the phone connected to the D6200 in the correct range and everything worked. To further confuse things we had a bit of a panic this morning on a MacMini connected to the D6200 (its our only stable internet connection) for a SourceConnect session when it just wouldn't connect to the internet. As it happend the Mac was set up to connect with DHCP using a manual address (because SourceConnect requires certain ports to be forwarded to a PC with a static IP). This had been working since I set it up but then that Mac is hardly ever re-booted - but it was yesterday morning. And even though the address was set to 192.168.10.160 the new DHCP router address it grabbed was 192.168.0.1 - hence no internet. By going to complete manual I was able to quickly solve the problem. 

So the D6200 was not doing this initially (at least on a wired connection) - I suspect a reboot might solve the problem but I'll list out my network for you anyway just in case I've done something stupid (quite possible).

Message 5 of 8
MondoTV
Aspirant

Re: D6200 Wireless assigning wrong IP address to DHCP clients

So I actually have three routers (apart from the modems) all with different purposes.

1. Netgear Prosafe JGSS16PE is a 16 port gigabit switch with 8 POE ports for the phone system. It sits on the 192.168.0.0 subnet and is connected to the Telstra modem.

2. TP Link T1700X-16TS is a 12-16 port 10gig E router which is use to conect my NAS's to video editing machines over 10Gbit connection. It sits on a 192.168.1.0 subnet

3. TP Link TL-SG1016 which is a 16 gigabit router that was connected up when the D6200 and new internet connection was introduced to allow access to that internet connection. The D6200 is connected to this router which sits on the 192.168.10.0 subnet. 

Both gigabit routers are connected to the 10GigE router. But not directly to each other. Some of the computers on the network are connected to all three (single cable -multiple IP addresses)  but some are only connected to the particular network they need - eg the MacMini is only connected the 192.168.10.0 network

Message 6 of 8
antinode
Guru

Re: D6200 Wireless assigning wrong IP address to DHCP clients

> [...] I actually have three routers [...]

   "switch" and "router" are spelled differently for a reason.

> [...] (apart from the modems) [...]

   Among the "modems" are you counting modem+routers like the D6200?
The router part of modem+router may be more important in this situation
than the modem part.

> 2. TP Link T1700X-16TS is a 12-16 port 10gig E router [...]

   According to TP-Link, it's a switch with some router capability.

 

      https://www.tp-link.com/uk/products/details/cat-40_T1700X-16TS.html

What you're doing with it is not entirely clear.

3. TP Link TL-SG1016 which is a 16 gigabit router [...]

   According to TP-Link, that's a switch, not a router.

 

      https://www.tp-link.com/us/products/details/cat-42_TL-SG1016.html

> [...] The D6200 is connected to this router which sits on the
> 192.168.10.0 subnet.

> Both gigabit routers are connected to the 10GigE router.  But not
> directly to each other. [...]

> [...] (Hint: If a device has multiple Ethernet ports, then "connected
> to device" is not enough detail.)

   Still true.  "But not directly" wouldn't save you.  A network switch
is very permeable; that's its whole reason for being.

   That description is too vague for me to understand what is actually
connected to what.

> [...] Some of the computers on the network are connected to all three
> (single cable -multiple IP addresses) [...]

   You lost me.  How does one computer interface get "multiple IP
addresses"?

   Between your network configuration and my feeble mind, at least one
of us is confused.

   Based mostly on speculation, my current guess is that you have
connected the LAN sides of the two modem+router devices together
physically, even though they use different LAN subnets.  One potential
problem with such an arrangement would be that when a client device
broadcasts a DHCP request, it could be received by the DHCP servers in
both (modem+)routers, and the client device would take its IP
configuration from the first DHCP server to respond.  Thus, a client
device might get a "192.168.0.x" address from (the DHCP server in) the
Telstra modem+router, or it might get a "192.168.10.y" address from (the
DHCP server in) the D6200 modem+router, depending on which gizmo has
more idle time at the moment.

> [...] I have two internet connections through two different providers
> (because one is so bad we had to get a second). [...]

   That might have been harmless if you had kept the two LAN segments
separate, but I suspect that you've connected them, and thus created one
unholy mess.  I wouldn't guarantee that it couldn't possibly be made to
work, but, as I said, running multiple, independent DHCP servers on one
LAN segment would be begging for trouble.  (Plenty of which you seem to
have acquired/generated.)

Message 7 of 8
MondoTV
Aspirant

Re: D6200 Wireless assigning wrong IP address to DHCP clients

Thanks for the insight - makes sense now. Yes it's a bit messy but on the whole it works. And I confused terminologies - sorry about that. How you connect to three different subnets is easy and I believe it's supported? You simply go into the TCP IP settings and advanced and add the other subnets. What is not supported is using two different default gateways (multiple homing).

Most of these problems came about because were supposed to switch to Australia's NBN when we moved in but bureaucracy reared it's ugly head and it was delayed for 12 months (even though apparently there's been a working physical connection in our basement for over 6 months). Having two internet connections is tricky. But the first one simply didn't work very well at all - under any circumstances - even when checked directly from the router modem with nothing else attached (and where it entered the building). Upload was a crawl - typically 10 - 30 KB/s and download was patchy - sometimes good but occasionally unworkable. This after multiple tech visits from different companies. We went through two providers (Optus then Telstra) before getting a separate line from iiNet that just worked. We'll be connected to the NBN soon so everything becomes a lot simpler. 

Thankyou for your help.  If anyone else experiences this problem based on the above advice, the simplest thing would be to turn off DHCP on one of the Internet routers and simply assign all the IPs manually or keep them physically separated as network.  

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