giving the SECOND router in my network a STATIC IP

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aocaocxbox

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Apr 15, 2015
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I have an Asus router connected to my isp, a switch from lan port #3 into another room. From that switch i have my devices and a second router ( which my isp supplied ). I basically want to turn DHCP off and run a server from behind the second router so that it doesn't conflict with the devices connected to my first router. Do i need to set a static IP to the router from using the DHCP table inside my first router or do i need to set the second routers static IP from inside the routers settings? thanks!
 
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You should set a static IP on the device that has the IP. Pick an address that is outside of the range of DHCP to avoid conflicts. Once you have done that don't use the WAN port unless you have an option to assign the WAN port to the switch somewhere in the configuration.

Your second router will then be only acting as a switch and wifi access point. You can change config by going to the static IP you set.
 
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If you connect the a cable from the switch to the WAN port on router #2, with DHCP turned off, the router should have internet access, but any device you connect to a LAN port will not receive an IP address (unless you assign one through Windows). It will technically work.

If you want other devices in your network to be able to see and communicate with the server you are setting up, then you should turn off DHCP and connect a cable from the switch to a LAN port on the router.

If you don't want other devices to be able to see and communicate with the server you are setting up, connect a cable from the switch to the WAN port on router 2, and turn DHCP on.
 
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Thanks for a detailed answer. I understand what your saying. I dont want the server to communicate with any devices connected to router #1, however i do want a couple of devices to communicate with the server so that i can create a domain controller and then connect a couple of PC's to the server. I guess these would be plugged in to the LAN ports on router #2? thanks once again.
 
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Correct. Anything connected to the LAN ports on Router 2 will be able to see and communicate with one another, but not to any device on router 1.

Also, make sure the subnet of router 1 is different than router 2.
Ex: Router 1 = 192.168.1.xxx, Router 2 = 192.168.2.xxx
 
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You may be looking at Subnet Mask, which is most likely 255.255.255.0. What I'm reffering to is Subnet which is the first three set of numbers in the IP address

Ex. "192.168.1"
 
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This is close but incorrect. If you want things to work reliably, you must set a static IP on the device with the IP. Setting a static IP on the main router using the MAC only creates a static DHCP entry. Since there is a good chance your config will disable the DHCP client for your router (you really don't want it anyway) this method of setting a static IP won't work.


This is also not correct. A default firewall in this configuration will allow anything on your second network complete access to your first network. Your first network will only be able to communicate to the second if you map ports with NAT. If you are just getting started, this is too complex.

You should get everything working on a single subnet with a single router. By disabling the DHCP server on the second router and connecting only the switch part (not the WAN port) you will be using it only as a switch. You can block access of one machine to another via software firewalls.

Once you get the simplest solution working, you can think about separating network segments using more than one firewall.
 
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Hi calculagator, my current setup is as follows and it appears to be working great at the minute although only been set up for a couple of hours.

I have my LAN port on router 1 connected to the WAN port on router 2. This seems to be great as I really don't want the second routers devices talking to the devices connected to router 1.

Nothing has clashed yet and both network seem to be separate as they cannot see each other.

I need DHCP enabled on router 1 for my family devices as my server won't be on constantly. Router 2 however is where my windows server will be running for just a couple of hours a day along with a few laptops I have just so that I can get used to Active Directory & things so I don't need this router 2 network to be able to see router 1 network.

I've setup my windows server and the laptop has connected to the domain controller with DHCP, DNS & AD installed, all seems to be running smoothly although it has only been running a short amount of time.

All the devices on the second router network ( including the router ) haven't got an Internet connection however this isn't a priority although I would like it to have a connection.

I have to be honest with you, I am finding this confusing & your answers don't make a lot of sense to me ( although I very much appreciate any help & response from you )

If you can see a major glitch which could mess up the network on router 1 please let me know as this could be disastrous!

Thanks for your time and please give me any suggestions ( in the lowest technical form possible )
 
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How is your current setup working great? Your second network is totally disconnected from the internet. The only reason that the devices in that second network cannot communicate with device on the first is because they are misconfigured. Once you get them online, they will have complete access to anything on network one-this is not a problem, but it is the opposite of what you seem to expect.

If you just want a disconnected network to test out AD, this is fine-don't even bother trying to connect to the first router, but if you want things to connect to a larger network, you need to take a different approach to configuration.

 
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Hm, I don't believe I am incorrect? I want so say I have set up something similar to this in the past. OP is trying to completely separate LAN1 and LAN2. By creating different subnets on each router he can achieve this.

But them again I may be incorrect. aocaocxbox should try both out suggestions to see what works best for him.
 
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If LAN1 is the 192.168.1 subnet and LAN2 is the 192.168.2 subnet, a request from a machine in LAN2 to the address 192.168.1.20 will go to the router for LAN2. The router will forward it directly to 192.169.1.20 since the default for most firewalls is to allow all outbound traffic. Unless you change the defaults of the firewall, the two subnets will only be partially separate.

Traffic from LAN1 to LAN2 will be blocked by the LAN2 router. Traffic from LAN2 to LAN1 will be permitted by the LAN2 router and never even hit the firewall for LAN1 since LAN2 is inside the LAN1 firewall.

This may be desired behavior and that's fine, but if the OP wants to learn basic networking, then the OP needs to know how things actually work.
 
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At the moment I believe it is acting as 2 completely different networks. This is what I need and will work fine however if I could get an Internet connection as well that would be even better.

The whole purpose of me separating the networks is because I need DHCP to be enabled on router 1 and the server inside network 2.

As for which method is best and why, that's where my knowledge ends haha!
 
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I have to agree you run router behind a router and it only provide security in a single direction and this is only because of how NAT works not because of any firewall setting. Pretty much the only way to stop this is to block the traffic but then you might as well not even plug the second router into the first router.

In most cases people want network 1 to be able to access network 2 not the reverse but there is no easy way to do this with consumer grade routers.
 
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As long as you don't care that devices on network 2 can access network 1 as well as the internet then there is no problem....but I though that was you whole purpose for setting this up.

It almost sounds like you want this setup in the reverse with your main network behind the second router to protect it.
 
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Maybe I missed something in this long thread.

The DHCP has little to do with how the networks are connected. All DHCP does is assign IP addresses. Your first router will give IP to the deivces connected to it and the second router will give out ip to the devices connected behind it.
 
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To a point it can be a problem. When you study this some more you can learn about helpers and how to run multiple DHCP server to allow for one to be turned off.....but you will then also start to see the shortcoming of consumer "routers".

You router1 should give ip to anything connected to its lan ports. If you want the LAN connected to router 2 to use your server for DHCP then you need to disable the DHCP on router2. What happens when you turn off the server is the device connected to the lan on router 2 will send out broadcast for DHCP and get no response which means they can not work. BUT this is only for devices that do not have a IP or it expired. If you set the lease time high they will continue to use it even if the server is off. Do not confuse the concept of DHCP server and GATEWAY. The gateway ip will always be the router.
 
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