Wi-Fi can't connect some devices

Software SW help
1

Running Turris OS 5.1.0 on MOX.
I am trying to migrate my IoT devices (which I still had on a separate ASUS RT-N16 router so far) to the Turris, on a seperate SSID.
For most devices it works, but for some, in particular SONOFF devices running the TASMOTA firmware, but also with an older Logitech Squeezebox Touch.
I observe devices that associate and then disassociate immediately from the WiFi.
Then the logfile is full of the messages like below.
I read in other forums that this seems to happen also on other OpenWRT based routers -> e.g. https://github.com/arendst/Tasmota/issues/2999 looks similar to me.

I already tried both Wi-Fi cards. No success.

Really strange is that exactly the same devices, on which I didnt touch the firmware, did connect perfectly well to the MOX but now they don’t any longer. And the log messages really don’t help me.

Anybody got an idea what might be wrong / where to search for the problem?

Sep  4 06:45:55 turris hostapd: wlan1-1: AP-STA-CONNECTED 80:7d:3a:6a:fb:a2
Sep  4 06:45:55 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 RADIUS: starting accounting session 56F557DEF47AD53B
Sep  4 06:45:55 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 WPA: pairwise key handshake completed (RSN)
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: AP-STA-DISCONNECTED 80:7d:3a:31:dc:bb
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:45:57 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: disassociated
Sep  4 06:46:01 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb IEEE 802.11: associated
Sep  4 06:46:01 turris hostapd: wlan1-1: AP-STA-CONNECTED 80:7d:3a:31:dc:bb
Sep  4 06:46:01 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb RADIUS: starting accounting session 8337908DD134D1EC
Sep  4 06:46:01 turris hostapd: wlan1-1: STA 80:7d:3a:31:dc:bb WPA: pairwise key handshake completed (RSN)
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:03 turris hostapd: wlan1-1: AP-STA-DISCONNECTED 80:7d:3a:6a:fb:a2
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:03 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: disassociated
Sep  4 06:46:07 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 IEEE 802.11: associated
Sep  4 06:46:07 turris hostapd: wlan1-1: AP-STA-CONNECTED 80:7d:3a:6a:fb:a2
Sep  4 06:46:07 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 RADIUS: starting accounting session 0823B45A3139EBF6
Sep  4 06:46:07 turris hostapd: wlan1-1: STA 80:7d:3a:6a:fb:a2 WPA: pairwise key handshake completed (RSN)
2

I might have found (part of) the solution - it seems that the network interface that I had created was somehow messed up and its netmask/broadcast address wasn’t configured.
I realized after a while that in Luci, the network wasn’t shown right (i.e. it didn’t show the “/24” for my IoT subnet 192.168.3.1/24)
I deleted and recreated the network in Luci and now the devices connect again to WiFi.
However, what I still cannot do is set it up in a way so that I have two separate SSIDs on one Wi-Fi card, one of which is tagged as a different VLAN and IP subnet so that I can isolate all these unsecure IoT devices. Basically I’m trying to build a guest network on which however some internal communication (with my IoT server) remains possible. I’ll open a new thread on that question.