Just want to mention for anyone else that might come across this thread searching for troubleshooting in the future - apex.local doesn't always seem to work from mobile chrome for me! Works fine from my laptop, but I think my phone tries jumping to mobile data and drops connection with the Apex.
#rurallife on day 7 of no internet service trying to set up my new DOS
This is a good point. Apex Local will only work over your LAN. If you want to access it on a mobile device, it's necessary to enable wifi and probably best to at least temporarily disable cellular data.