Can I set up our wifi so that I can turn off the wifi on my kids electronics at night and not effect the rest of the house

Check the settings you must have turned auto turn off wifi to on state after some time

Air plane mode simply turns off the WiFi. Go to settings and turn it back on again!!!!!

Often I find that either my kids or some application has managed to put the Nabi in "Airplane" mode - that means the WiFi is off. In parent (Daddy or Mommy mode) go to the "Settings" application and hit the WiFi option. Make sure it's not in Airplane mode and then confirm it's connected to the right WiFi source (router, hotspot, etc.) for your location.

If you can click on your wifi and pick "forget" do that and then restart the tablet and try again. If that doesn't work try going to settings and resetting it to factory then it will be like a new one, if you can do it without wifi some tablets wont let you past the wifi screen until you sign on.

Here is the remedy for that error:
We've heard a few reports of Wifi connectivity issues recently, among them 'Authentication error'. If you receive this message, our recommended remedy is to remove all Wifi connection information from your Meep, turn off your Meep, reboot your router, then turn on your Meep and re-add the Wifi information. Follow these steps exactly in this order to resolve this error message:
1. Remove all Wifi network information from the Meep's settings
2. Reboot your router
3. Re-add the Wifi network information to the Meep's settings
4. Reboot the Meep.

Please contact the OSI call center for all Wifi related issues.

When you reset the tablet your tablet wifi settings, wifi name and password will be erased. You have to detect your wifi on the tablet, connect to it and enter password right?

Go to settings and then wifi if it is off switch it on and then select your wifi router and enter your password

Something has changed in your wifi settings first check wifi is turned on (press menu On the right hand side next to the battery it will say off is wifi is turned off) the first option in the menu is turn on wifi.
if wifi is on click home -> menue and go to settings scroll down to wifi see if your wireless network is there if it is not but other networks are there it is a problem with your house network not the kindle

if your house network is there with a message next to it saying connect then click connect if it says forget then forget it and connect again.

If the device fails to connect you should go into settings push menu and then restart if still no luck go to settings and click reset to factory defaults and try again through wifi settings if this does not work their is a fault with your device and you have to talk to amazon

amazon will charge you to replace the device if you tell them anything like you dropped it so as far as you know it was working when you went to bed you woke up the next day and it didn't work ;)

let me know if this helps

Hold the on switch and menu button together for a hard reset. If you can reset it, there may be an issue with your motherboard. If apple doesn't replace it for you, You can get the board at iPad Repair and there is a guide that shows you how to put in the part at Electronics Repair Guide.