I'm running stretch on a pi3 with motion. I can browse this no problem from a pc for as long as I've cared to try but when I try to access it through firefox on my android phone, bang networking goes down. No motion, no ssh, but through a local login it seems fine, except there's no access to the network. Wlan0 still has the same ip, but none of the following work to restart networking;
sudo service networking restart
sudo ifdown wlan0, sudo ifup wlan0
sudo systemctl restart networking.

Everything comes back as expected after a reboot. Can't find anything in the logs, just using the internal wifi. This is always repeatable. Only thing I can find is "brcmfmac: brcmf_sdio_hostmail: unknown mailbox data content: 0x40012" in journalctl -b

Thanks!