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RT-AC88U: DHCPRequest via 2.4GHZ Wlan does not work properly (Repeater, DHCP)

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dokape

Occasional Visitor
I was searching for a solution of my problem now over one year...

Problem:
I have a repeater (tried several models, even Asus RP-AC66u, using now a TP-Link RE500):
This Repeater was linked with the RT-AC88U on 2.4Ghz Wlan.
With Asus-Firmware 380.3341 everything worked fine.
Repeater got a static IP-Address, I tried assigning by DHCP-Server based on MAC-Adress or static/solid address saved in the repeater.

Switching to newer Asus-firmware (and i tried Merlin firmware) I got the problem, that the repeater got no ip-Address by the router. A view into routers log:
Repeater tried DHCPDiscover, Router made a DHCPOffer, but the Repeater did not send - or the router did not receive - a DHCPRequest.
Well, for other clients than a Repeater (iPad, iPhone, Brother-Label-Printer, Android-Phones, Alexa, Google mini, Chromcasts) everything worked fine... (until they are not connected by the Repeater)
I went back to firmware 380.3341 (but this has several other annoying bugs :-( )

I assumed there could by a bug in the actual DHCP-Server by Asus-FW.
So I moved the DHCP-Server out of the RT-88U to my RaspberryPi in the network.
Worked fine with Router ASUS FW380.3341.

I installed Asus FW 384.x (actual), It worked for some hours (well 1 or 2 lease-times) than it began again:
DHCPDISCOVER: OK
DHCPOFFER: OK
But no DHCPREQUEST nor DHCPACK (just for the 2.4Ghz linked Repeater) and connected devices.
But the DHCP is done by a raspberry pi!
A reboot of the RT-AC88U leads to run it sometimes, but only for 1 or 2 lease-times.
Same with Merlin-Firmware 384.7_2 (I assume, in Merlin there isn't a difference in that case to AsusWrt)

Moving back to Asus-Firmware 380 -> Hey! Everything works again fine. (DHCP still done by RaspberryPi)

Assuming, newer Firmwares than 380 (eg 382 and 384) changed something in the internal routing by wlan with the DHCP. Perhaps packages with this tag are discarded?

I changed the configuration: I linked the repeater not by the 2.4Ghz, instead I linked the repeater by the 5 Ghz AC-Wlan.

And now the interesting: It works fine with Asus-Firmware 384.32799 and the Merlin-Firmware 384.7_2.
Reboot the Repeater RE500: DHCPDiscover, DHCPOffer, DHCPRequest an DHCPACK comes perfekt, every reboot, every end of lease. perfekt, wunderful. But only on the 5Ghz Wlan Link.
With 2.4Ghz Wlan-Link the DHCPRequest an DHCPACK are missing. No connection. Until Reboot of RT-AC88U and to the next DHCP-Lease Refresh.

So I assume there is a bug by discarding/processing "DHCPRequest" network packages from repeaters by routing them from 2.4Ghz Wlan receiver in RT-AC88U to the internal switch.


I had my problem first described Oct, 2017 in this thread:
https://www.snbforums.com/threads/rt-ac88u-and-tp-link-re355-no-ip-adress-assigned-to-devices.41719/

Keywords: RT-AC88U, IP-address, assign, Repeater, DHCPRequest, Logfile, WLAN, WIFI,
 
seems nobody is interested in your problem :(

I cant help too, but as with stock and Merlin he wont do anything and you have to got it solved by Asus themselves.
Open a feedback to them in router GUI and insist in bug fix, maybe youre lucky and they will do something or answer at least.

Here I think is a very similar post to yours: https://www.snbforums.com/threads/repeater-dhcp-issues.47494/page-3#post-443266
and here: https://www.snbforums.com/threads/a...hz-radio-malfunction.46272/page-3#post-444092
 
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