@marian , I was able to replicate it and when running dmesg, I see the following message:
[ 390.539854] R0: [VosMCThread][02:38:25.067557] wlan: [3231:E :PE ] limProcessAssocReqFrame: 914: Max Sta count reached : 2
Changing max_num_sta in hostapd.conf did not help.
After doing a little bit of digging, it seems like this may be a hardware limitation of the wifi hardware on VOXL1 in SoftAP mode : https://android.googlesource.com/kernel/msm.git/+/android-msm-bullhead-3.10-n-preview-1/drivers/staging/qcacld-2.0/CORE/MAC/src/pe/lim/limProcessAssocReqFrame.c#847 .
It could also be a setting somewhere low level and unfortunately we don't have any information on that. Sorry about that.
The wifi module on VOXL1 is QCA6174.
Alex