SOLVED: DHCP Configuration Issue on ASUS RT-AX88U Pro - Wired vs. Wireless

[DrViper]

Hello everyone,

I'm facing a peculiar issue with my ASUS RT-AX88U Pro router (192.168.1.254). The DHCP server is set to distribute IP addresses between 192.168.1.155 and 192.168.1.195.

While wired connections respect this range, wireless connections receive completely random IPs in the 192.168.0.x range, ignoring the DHCP configuration entirely. Despite this, these devices show up in the client list as DHCP instead Static.

I have attempted to force 192.168.1.X range by registering the MAC addresses and assigning 192.168.1.x IPs in the "Manually Assigned IP" Section, but this has not resolved the issue.

Is there a specific DHCP adjustment for wireless clients that I'm missing?

Could anyone also suggest some SSH commands that might help diagnose this problem?

Thanks,

 

[bbunge]

What are the settings for LAN/LAN IP/IP Address and LAN/LAN IP/Subnet Mask?

 

[DrViper]

Wireless devices are all on the main network.

LAN/LAN IP/IP Address: 192.168.1.254
LAN/LAN IP/Subnet Mask: 255.255.255.0

IP Pool Starting Address: 192.168.1.155
IP Pool Ending Address: 192.168.1.195

 

[bennor]

@DrViper, what firmware is the RT-AX88U Pro running?
Have you checked the client devices exhibiting the issue to see if they are randomizing their MAC addresses as a security feature? Typically those devices will have an option in their settings to disable the MAC randomization.

 

[DrViper]

@bennor, I have checked and disabled the MAC address randomization feature on devices that had it enabled, such as iPhones, ensuring that the real MAC address is used when obtaining IPs from the DHCP server.

However, even with this feature turned off, the iPhone, for example, still does not comply and continues to receive addresses in the 192.168.0.x range.

RT-AX88U firmware current version : 3.0.0.6.102_33340-g5c167ca_345-gf3514

 

[bennor]

However, even with this feature turned off, the iPhone, for example, still does not comply and continues to receive addresses in the 192.168.0.x range.

What is the Asus router connected to upstream? A ISP router? If so check that router's WiFi and disable it if needed. Or do you have any other WiFi routers, mesh nodes, extenders, etc. in the home the affected devices could be connecting to?

As a troubleshooting step on the affected devices, instruct the device to forget or delete the WiFi connection to the Asus router, then create a new connection to the Asus router.

 

[DrViper]

I isolated the RT-AX88U router from the cable modem and noticed that the DHCP started working correctly.

After this, I reset the cable modem to factory settings and and reconfigured it to ensure that DHCP was disabled and the equipment was in bridge mode.

Once I did that, the DHCP issue no longer occurred.

Thank you all for your help!

 

[Tech9]

You had this ISP modem/router plugged into an RT-AX86U Pro port not configured as WAN.