Venue 8 Pro cannot log in / Wifi failure

Suddenly I cannot login to my Dell Venue 8 Pro - 5830 w/Windows 10 

The PIN screen appears but the virtual keyboard does not pop up, so no PIN can be entered.

In the past, touching the PIN box would bring up the keyboard. 

A bluetooth mouse is working (cursor appears) but no keyboard = No PIN  or password.

Maybe related-  no wireless connections are found. I have also been experiencing regular WIFI failure which is fixed by toggling the "D0 packet coalescing" setting of the onboard network adapter. It doesn't seen to matter whether that is on or off, just changing its state seems to get the wireless working again.