Just to be clear: this has nothing to do with the (known) performance and instability issues of the Archer.
TL;DR: Android devices (even recent ones) can connect but not get internet access through the 5 GHz WiFi. They do not have issues with the 2.4 GHz interface, and other machines (e.g. Windows laptops) can connect and have internet access through the 5 GHz interface.
Hello, I am getting crazy about this problem. I understand this is gonna be a tricky and weird problem, so please bear with me. I will try to start generic and then we can pinpoint the problem step by step, feel free to ask questions or config files.
I have a TP-Link Archer C7 V2 running OpenWrt 21.02.1 r16325-88151b8303 / LuCI openwrt-21.02 branch git-21.295.67054-13df80d. This is my home router, I haven't touched the config for a while except minor tweaks. I think the problem started appearing when upgrading from 20.something to 21.02 but cannot be 100% sure about this, all I know is that everything was working fine until a few months ago.
Long time ago I set up a funny configuration: by playing around with VLANs I created two interfaces: "LAN" and "DMZ". LAN devices can access WAN and DMZ but DMZ devices can only access WAN. DHCP is enabled on both networks (some are static addresses) and DNS is provided to both networks. I have even configured some tagged ports of the switch so that 2 ethernet ports are LAN and 2 are DMZ. Notice that, via ethernet cable, everything works as intended.
Then there is the two WiFi interfaces: radio0 (5 GHZ, Qualcomm Atheros QCA9880 802.11nac) and radio1 (2.4 GHZ, Qualcomm Atheros QCA9880 802.11nac).
radio0 provides the GUEST WiFi and is attached to DMZ
radio1 provides the HOME WiFi and is attached to LAN
Both use WPA3 through WolfSSL and various security optimizations (KRACK countermeasures etc). GUEST WiFi works perfectly but HOME does not: my Android devices see the network, manage to connect and receive an IP in the correct range, they are also automatically configured with the right DNS and gateway. However, they report "no connection" and do not resolve any address.
Just a weird idea, but perhaps also give the openssl variant of wpad a try (instead of wolfssl). Wolfssl caused issues with hostapd in the past, while those should be solved (at least there don't seem to be open issues remaining), it's probably good to rule this out as well.
Hello again and thanks, unfortunately didn't work out. First of all an errata to what I wrote in the first post (unfortunately I cannot edit it anymore): it is not true that Android devices get assigned a correct IP, I had actually configured it manually exactly because they, in fact, don't. They see the network and when they try to connect I can see the device connecting from LuCi but the Android device gets stuck on "Receiving IP address..." and nothing happens. It almost looks like DHCP is not working (only for Android devices and only on that interface).
What I did:
changed the channel of the GUEST WiFi to 36 (but notice that GUEST is the WiFi that is working correctly, the one that gives me headaches is the HOME one)
OK I'll try, but can you please argument more on how this could possibly be related to a (seemingly) DHCP or routing problem on the HOME wifi that only affects Android devices? Is there some known issue of interoperability with, I don't know, the radio driver or whatever?
I will try also to remove these options when I come back home and report on the outcome. Frankly I don't even remember where they come from lol
Yes OK but as I wrote before Android devices have no problems connecting to the GUEST WiFi, which is also using sae-mixed. So I really don't think this is related. And regarding the channels, I chose those because they were looking less crowded in my area (I did a scan). Regardless, I have adopted all these suggestions and nothing changed, but thanks for trying.
Also disabled these options but nothing changed. My wireless conf file now:
Ok, your HOMEWIFI uses 802.11w. Try to not use this one. If that does not help, temporarily switch Homewifi and guestwifi in order to see whether the problem is related to your network config or to your wireless config..., meaning temporarily assign homewifi to dmz and guestwifi to lan. What happens then ?