OpenWRT on WS-AP3705i DHCP only in WiFi

Hello everyone,

I have a router (which I can't touch, since it is managed by the provider) which acts as a gateway (192.168.1.1) and which releases DHCP from the address 192.168.1.10 to the address 192.168.1.90.
Currently the AP uses the gateway's DHCP, and all the addresses of the devices that connect to WiFi are released by the gateway 192.1.68.1.1.
I would like to have the possibility for my AP to independently release DHCP without them conflicting.
example:
Gateway 192.168.1.1 DHCP on Ethernet network (range 192.1.68.1.10 - 192.168.1.90)
DHCP AP from address 192.168.1.200 to address 192.168.1.254 without also being released for devices connected to the Ethernet network.
It's possible ?
Thanks in advance!

Multiple DNSes on the same subnet is a bad idea, even if they don't overlap.

I had this setup where the dhcp was not colliding. I set up a Dhcp on AP and set the range different from the main router. But you can forget the fast roaming between APs, because of different IP. Moreover, when you move the AP to other location and do not set different dhcp range, weird things will happen on your network. You will have ip in router's ip address range, but the router does not know the MAC address so it won't know where to send eth packets, since the ip was provided with other ap and the MAC address sits on that device. The result will be a collapsing lan and lost connectivity.

As long as you don't mind having your ethernet devices on a different subnet, you can simply setup the device in standard routing mode with a wireless uplink.

https://openwrt.org/docs/guide-user/network/wifi/connect_client_wifi

Otherwise, no, you cannot do what you are proposing (there are actually several technical reasons for this).

Would it be possible to bypass the switch and the router and create an internal subnet to the AP with address 192.168.2.xx which therefore only serves the WiFi?
With a routing rule internal to the AP?

What exactly do you mean by that?

Well, that was the link I shared earlier... you need the routing to create a new subnet. It can serve ethernet and/or wifi. Your uplink would be a 'wireless wan' and you'd just use the router in normal routing mode.

For example:
now dhcp assigns it to the main router (192.168.1.1) which is connected to a switch.
The PoE ethernet cable that goes to the AP starts from the switch.
I would like to create an internal routing that translates the 192.1.68.1.x network towards the 192.168.2.x network only for clients connected via WiFi and which can still see the 192.168.1.x internal network.
In short, with its own internal DHCP Server, which assigns the 192.168.2.xx network to all clients and acts as routing to the 192.1.68.1.x internal network, where I have the NAS and other PCs on Ethernet.

What you are describing is effectively standard routing. The default config of OpenWrt would do what you want except for the OpenWrt lan which defaults to 192.168.1.0/24 and you would need to change that to 192.168.2.0/24.

Exactly.
Do you have an simple configuration example?

The default config will do it. Just change the address.

Or if you need to connect via WiFi, read the link I shared earlier.

In the link you shared it is intended to connect to a wifi network as a repeater, I need it to be from the AP's LAN port to the AP's wifi.
That is, the router's Ethernet network 192.168.1.x arrives in the AP port and I would like my AP to assign the 192.1.68.2.x network to the wifi clients

image

in this image, I would like the IP address of the AP to always be 192.168.1.2, but that the hosts connected to it are on the 192.168.2.x subnet.
The image exactly represents the situation of my network.
Thanks