Apple devices can't access Internet if IPs are DHCP-assigned

[GreyGoose]

DIAGRAM UPDATED
Apple devices cannot connect to an ASUS RT-AC66U configured as a repeater when set to use DHCP-assigned IP addresses - they can only connect when using statically-defined IP address settings (IP, mask, router IP & DNS).

Why is this not working with DHCP-assigned IPs for Apple devices?

The ASUS RT-AC66U repeater connects via WiFi to a UniFi Dream Machine (which is the Internet gateway at 192.168.1.1) and has an IP address assigned by DHCP on the UDM gateway.

The symptom on iPhones and iPads is the "activity" wheel on the Apple Wi-Fi page goes round forever while trying to get an IP, unsuccessfully.

However, laptops do get an IP and can connect to the repeater on 2.4 and 5 GHz WiFi, and access Internet through the UDM.

If IP addressing is set manually (IP, mask, router IP & DNS) on the Apple devices then they can connect to the AC66U repeater and through to the Internet.

• RT-AC66U Firmware Version: 3.0.0.4.382_52287 (latest).
• Apple devices: iPhone 6S (iOS 15.1) and iPad Air 2 (iOS 15.1).
• The Apple devices have no VPN.
• Network Settings have been reset on the iPhone and iPad.
• The Apple devices have been rebooted.

Any ideas why Apple devices cannot use DHCP, or how to troubleshoot this?

Thanks

 

[GreyGoose]

Please help - Any ideas why Apple devices cannot use DHCP, or how to troubleshoot this?
Thanks

 

[sfx2000]

Apple does not have issues with DHCP.

Take the repeater out temporarily, and things should work...

 

[OzarkEdge]

Apple devices cannot connect to an ASUS RT-AC66U configured as a repeater when set to use DHCP-assigned IP addresses - they can only connect when using statically-defined IP address settings (IP, mask, router IP & DNS).

Why is this not working with DHCP-assigned IPs for Apple devices?

View attachment 37503

The ASUS RT-AC66U repeater connects to a UniFi Dream Machine (which is the Internet gateway at 192.168.1.1) and has an IP address assigned by DHCP on the UDM gateway.

The symptom is that the "activity" wheel on the Apple Wi-Fi page goes round forever while trying to connect, unsuccessfully.

However, laptops can connect to the repeater on 2.4 and 5 GHz WiFi, and access Internet through the UDM.

If IP addressing is set manually (IP, mask, router IP & DNS) on the Apple devices then they can connect to the repeater and Internet.

RT-AC66U Firmware Version: 3.0.0.4.382_52287 (latest).

Apple devices: iPhone 6S (iOS 15.1) and iPad Air 2 (iOS 15.1).
The Apple devices have no VPN.
Network Settings have been reset on the iPhone and iPad.
The Apple devices have been rebooted.

Any ideas why Apple devices cannot use DHCP, or how to troubleshoot this?

Thanks

Is the AC66U WAN wired to the UniFi router LAN, and configured as an Access Point (AP)?

OE

 

[GreyGoose]

@sfx2000 and @OzarkEdge - I have corrected the diagram to show that the ASUS RT-AC66U is connected via WiFi to the UniFi Dream Machine.
The AC66U is 20m from the Dream Machine, and configured as a WiFi Repeater, not an Access Point.

I'm baffled why the Apple devices cannot get an IP address from the UniFi's DHCP, but if IP addresses are assigned manually, then the Apple devices do get Internet access. Is there anything in the AC66U settings that would prevent it from relaying DHCP requests to the UniFi gateway?

Thanks

 

[OzarkEdge]

@sfx2000 and @OzarkEdge - I have corrected the diagram to show that the ASUS RT-AC66U is connected via WiFi to the UniFi Dream Machine.
The AC66U is 20m from the Dream Machine, and configured as a WiFi Repeater, not an Access Point.

I'm baffled why the Apple devices cannot get an IP address from the UniFi's DHCP, but if IP addresses are assigned manually, then the Apple devices do get Internet access. Is there anything in the AC66U settings that would prevent it from relaying DHCP requests to the UniFi gateway?

Thanks

I wonder if this is a 'Disable Private Addresses on Apple clients with connection issues' issue(?).

OE

 

[Ronald Schwerer]

Are the Apple devices configured to use its static MAC or are the MACs random? If your DHCP is locked-down to only provide IPs to known devices, random MACs would explain this issue.

 

[GreyGoose]

@OzarkEdge and @Ronald Schwerer I have tested with "Private Address" on and off on iPhones and iPads, but in both cases Apple mobile devices just do not get an IP address when set to "Configure IP: Automatic" and "Configure DNS: Automatic".

The DHCP server only issues one reserved IP address to a specific MAC address, for a Raspberry Pi. The UniFi Dream Machine will issue an IP to any device that joins the network - it is is not locked to known devices only.

Any non-Apple device can connect to the RT66U, get a DHCP-issued IP from the UDM, and connect to the Internet. Yet Apple mobile devices cannot - baffling??

 

[OzarkEdge]

@OzarkEdge and @Ronald Schwerer I have tested with "Private Address" on and off on iPhones and iPads, but in both cases Apple mobile devices just do not get an IP address when set to "Configure IP: Automatic" and "Configure DNS: Automatic".

The DHCP server only issues one reserved IP address to a specific MAC address, for a Raspberry Pi. The UniFi Dream Machine will issue an IP to any device that joins the network - it is is not locked to known devices only.

Any non-Apple device can connect to the RT66U, get a DHCP-issued IP from the UDM, and connect to the Internet. Yet Apple mobile devices cannot - baffling??

Is the UDM firmware current? Can you swap in a spare/old router to see if it works with the Apple clients? Could other network clients be interfering... what does the PI do?

OE

 

[GreyGoose]

Yip, the UDM is the latest firmware. And I've scoured the settings to see if there's anything in the ASUS that could prevent it relaying DHCP requests, but cannot find anything. It is strange that a DHCP request from a Windows laptop does get relayed from the AC66U to the UDM, and the reply gets relayed back through the AC66U to the Windows device. I have not successfully traced where this stops for Apple devices (yet) - the verbose logs do not show anything telling, much to my surprise.

 

[ColinTaylor]

The only things on the Asus I can think of that might be somehow relevant are;

1) Using guest WiFi networks instead of the primary networks.
2) Setting "AP Isolated" to Yes in the WiFi Professional settings.

 

[GreyGoose]

Thanks @ColinTaylor but I do not see an option in the RT66U for a guest network, or "WiFi Professional" or an "AP Isolated" setting when in Repeater mode. I think they are only available in wired AP mode.
@OzarkEdge this is the only device I currently have that can be configured as a repeater, and it has fantastic WiFi range as a repeater. The Pi is just a Plex server, and unplugging it doesn't change the iPhone and iPad from not being able to get an IP via DHCP.

 

[OzarkEdge]

View attachment 37559

Is there a network reset on the Apple devices? Forget and recreate connections?

Change the WiFi signal channel, smaller bandwidth?

Can the Apple devices connect to the UDM WiFi (UDM directly)?

I wonder what you get if you wire the 66U as an AP? With UDM WiFi OFF?

OE

 

[GreyGoose]

I've reset the Apple devices' network settings, and even reset the iPhone 6S completely - still no connection to the AC66U unless IPs were manually set.

In repeater mode there's not a lot that can be set on the AC66U - just the SSID it's connecting to and the name and creds of the 2 & 5 Gig SSIDs it creates for devices to connect to - I see nowhere to change the channel settings. But whatever they are, they work very well if iPhones and iPads are manually addressed.

Apple devices can connect to the UDM fine. And also to the AC66U (using DHCP) when it was the router (it has been retired in favour of the UDM and a growing network of UniFi APs.

Thanks for your suggestions, but even if the AC66U was configured as a wired AP and DHCP worked, it wouldn't solve the repeater scenario. I'm going to inspect logs on the AC66U to see if DHCP requests show up, and then if they're forwarded to the UDM. But I'm surprised how little there is in the logs.

 

[GreyGoose]

I also have a Victron inverter connecting successfully to the RT-AC66U repeater, and the inverter IP & DNS addressing are both set to Auto - so Windows and this non-Apple device can use DHCP ok.
Diagram updated again...
It's just iPhones and iPads that have to be manually IP-addressed. A mystery

 

[OzarkEdge]

Apple devices can connect to the UDM fine. And also to the AC66U (using DHCP) when it was the router

Could try the previous AC66U firmware(?)

I'm about out of guesses.

OE

 

[sfx2000]

The AC66U is 20m from the Dream Machine, and configured as a WiFi Repeater, not an Access Point.

Might be timing out on the DHCP callflow - 20 meters is a bit of a stretch for some locations...

 

[ringlord]

Is there a ISP modem/router between the UDM and the internet?
This was the case for me, and that router would also send DHCP NACK, even if DHCP was turned off on that router.

 

[Palmen]

@GreyGoose Did you ever find a solution to your problem?

I have the exact same situation with iOS devices (15.1 and 15.1.1, not tried 15.2 yet) not being able to connect to a repeated WiFi using DHCP - static IP works just fine. There is a slight difference in that I have a RT-AX55 (3.0.0.4.386_45934) connected to the UDM (UniFi OS 1.11.0 and Network 6.5.55).

macOS 12.0.1, Win10, Win11 and a couple of different Androids work just fine.

 

[wouterv]

How are the LAN settings of the RT-AC66U as wireless repeater?