Many thanks for your investigations! SD card issues are solved, I obviously stopped the system during a write operation - after a shutdown (and card check with an PCs adapter) the errors are gone. But this had no impact. What I did for comparison: I applied the same semi-manual netplan / networkd / hostapd setup sequence to an OrangePiZero, also trixie ( v26.8 rolling for Orange Pi Zero running Armbian Linux 6.18.37-current-sunxi). And guess what: this works without a hiccup! So I looked into the syslog output when connecting. This is the output for the OPi (success!): 2026-07-07T20:47:35.333876+02:00 orangepizero hostapd: wlan0: STA ee:79:bc:4f:11:45 IEEE 802.11: authenticated 2026-07-07T20:47:35.336530+02:00 orangepizero hostapd: wlan0: STA ee:79:bc:4f:11:45 IEEE 802.11: associated (aid 1) 2026-07-07T20:47:35.406476+02:00 orangepizero hostapd: wlan0: STA ee:79:bc:4f:11:45 RADIUS: starting accounting session 01344FB459DCA3B1 2026-07-07T20:47:35.407484+02:00 orangepizero hostapd: wlan0: STA ee:79:bc:4f:11:45 WPA: pairwise key handshake completed (RSN) 2026-07-07T20:47:35.409156+02:00 orangepizero kernel: ieee80211 phy0: CCMP_PAIRWISE keylen=16! And this is the output for the failing BPi: 2026-07-06T17:54:46.957014+02:00 bananapipro hostapd: wlan0: STA 22:50:7b:ac:e3:2e IEEE 802.11: associated 2026-07-06T17:54:46.983182+02:00 bananapipro hostapd: wlan0: STA 22:50:7b:ac:e3:2e RADIUS: starting accounting session 9B014BB4D748D33B 2026-07-06T17:54:46.984065+02:00 bananapipro hostapd: wlan0: STA 22:50:7b:ac:e3:2e WPA: pairwise key handshake completed (RSN) 2026-07-06T17:55:28.848201+02:00 bananapipro hostapd: wlan0: STA 22:50:7b:ac:e3:2e IEEE 802.11: disassociated or: (worst case) 2026-07-07T16:52:15.236724+02:00 bananapipro hostapd: wlan0: STA 22:50:7b:ac:e3:2e IEEE 802.11: associated 2026-07-07T16:52:15.270595+02:00 bananapipro hostapd: wlan0: STA 22:50:7b:ac:e3:2e RADIUS: starting accounting session E501E4B1A6220EF1 2026-07-07T16:52:15.271648+02:00 bananapipro hostapd: wlan0: STA 22:50:7b:ac:e3:2e WPA: pairwise key handshake completed (RSN) 2026-07-07T16:52:30.104160+02:00 bananapipro kernel: ieee80211 phy0: brcmf_psm_watchdog_notify: PSM's watchdog has fired! 2026-07-07T16:55:07.185663+02:00 bananapipro kernel: brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout 2026-07-07T16:55:07.185794+02:00 bananapipro kernel: ieee80211 phy0: brcmf_cfg80211_get_channel: chanspec failed (-110) 2026-07-07T16:55:09.745805+02:00 bananapipro kernel: brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout 2026-07-07T16:55:09.749180+02:00 bananapipro kernel: ieee80211 phy0: brcmf_cfg80211_get_tx_power: error (-110) 2026-07-07T16:57:18.001649+02:00 bananapipro kernel: brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout 2026-07-07T16:57:20.561670+02:00 bananapipro kernel: ieee80211 phy0: brcmf_proto_bcdc_query_dcmd: brcmf_proto_bcdc_msg failed w/status -110 2026-07-07T16:57:20.562221+02:00 bananapipro kernel: ieee80211 phy0: brcmf_cfg80211_get_station: GET STA INFO failed, -110 2026-07-07T16:58:23.281661+02:00 bananapipro kernel: ieee80211 phy0: brcmf_proto_bcdc_query_dcmd: brcmf_proto_bcdc_msg failed w/status -110 2026-07-07T16:58:23.282246+02:00 bananapipro kernel: ieee80211 phy0: brcmf_cfg80211_get_channel: chanspec failed (-110) .... (more errors) The ip link/ ip route is identical, for the OPi also the networkctl output is clean: root@orangepizero:/home/thomas/work# networkctl IDX LINK TYPE OPERATIONAL SETUP 1 lo loopback carrier unmanaged 2 end0 ether enslaved configured 3 wlan0 wlan enslaved configured 5 br0 bridge routable configured 4 links listed. I also started to compare the log outputs for the start of hostapd, many things look equal / "similar" (maybe due to different underlaying hardware). I could provide the 2 (streamlined) logs, here only the most obvious deltas: nl80211: flush -> DEL_STATION wlan0 (all) --> nl80211: Station flush failed: ret=-14 (Bad address) (BPi) <none> (OPi) <TX queue cmds OPi> nl80211: TX queue param set: queue=0 aifs=1 cw_min=3 cw_max=7 burst_time=15 --> res=0 nl80211: TX queue param set: queue=1 aifs=1 cw_min=7 cw_max=15 burst_time=30 --> res=0 nl80211: TX queue param set: queue=2 aifs=3 cw_min=15 cw_max=63 burst_time=0 --> res=0 nl80211: TX queue param set: queue=3 aifs=7 cw_min=15 cw_max=1023 burst_time=0 --> res=0 <TX queue cmds BPi> nl80211: TX queue param set: queue=0 aifs=1 cw_min=3 cw_max=7 burst_time=15 --> res=-95 Failed to set TX queue parameters for queue 0. nl80211: TX queue param set: queue=1 aifs=1 cw_min=7 cw_max=15 burst_time=30 --> res=-95 Failed to set TX queue parameters for queue 1. nl80211: TX queue param set: queue=2 aifs=3 cw_min=15 cw_max=63 burst_time=0 --> res=-95 Failed to set TX queue parameters for queue 2. nl80211: TX queue param set: queue=3 aifs=7 cw_min=15 cw_max=1023 burst_time=0 --> res=-95 Failed to set TX queue parameters for queue 3. Question is, if I have to give up on the hardware or try a SW workaround (as my old solution running on BPiPro Bookworm / NM: wifi set to umanaged and using a hand-made hostapd / dnsmasq / iptables solution - will this work for Trixie? Do not know.)

You disable the zram swap, I forgot how, I think look in /etc/default/ambian* files. Else disable or mask the specific .service file.

This is no success, it id wrong implementation, it is AI, from concept/principel it seems OK, but implementation is NOK So I think I stop experimenting and will use NM if bridged WiPi AP is needed, I have several optional working in Debian Trixie and other distro. For wired lines, systemd-networkd with brideges and VLANs work OK. As said already, Debian has netplan optional, so in Armbain Trixie I simply do apt purge --autoremove netplan.io (and install NM via apt install network-manager). Then via nmtui it is easy to setup a bridged WiFi AP, no hostapd needed. By the way, you have several errors w.r.t. your SD-card, might be a sunxi kernel issue, but also you brad SD-card or so.

Problem seems to be that the wlan0 somehow must have a carrier, else it cannot be added to the bridge. A quick hack in a running system, done via serial terminal is: root@raspi7:/etc/systemd/network# systemctl stop systemd-networkd ; systemctl restart hostapd ; systemctl start systemd-networkd Then: root@raspi7:/etc/systemd/network# networkctl IDX LINK TYPE OPERATIONAL SETUP 1 lo loopback carrier unmanaged 2 eth0 ether enslaved configured 3 br0 bridge routable configured 4 wlan0 wlan enslaved configured I did some more testing and also with wlan0 stated as fail, I could browse the internet on my smarthone via the AP. Note that in the meantime, I also simplified the 10-* files a bit, added a MACAddress same as eth0 for br0, so my routers issues same IP address when DHCP, but that is not fundamental to this issue I think, i more how I do it also via NM and how it was automatically in old Linuxes. Google/Gemini suggests to add Before=systemd-networkd.service to hostapd.service, maybe I try, but I find that a dirty hack, it should be already in the OS, although Trixie is not the latest Linux.

I made a comparable setup on a raspberrypi3b+ and I see in the journal: Jul 07 17:37:01 raspi7 systemd-networkd[292]: wlan0: Configuring with /etc/systemd/network/10-wlan0.network. Jul 07 17:37:01 raspi7 systemd-networkd[292]: wlan0: Failed to set master interface: Device does not allow enslaving to a bridge. Operation not supported Jul 07 17:37:01 raspi7 systemd-networkd[292]: wlan0: Failed It worked many years ago when it was buster or bullseye and using ifupdown interfaces network setup. Also ported that to NetworkManager before Bookworm and that works, also in Trixie. This is my first manual setup, as it is Debian Trixie based, I can avoid the use of netplan.io. I remember I have seen this issue somewhere, It might be a newer release systemd issue. But have not searched internet now, will see later why this is.