What Network Authentication Failed is about?

SOURCE: Phone doesn't collect email automatically or switch between work/home WiFi and mobile network outside the office

Download a free app called HandyWi from the Nokia Ovi Store. This app will allow you to manage your connections in such a way that Wi-Fi is prioritised and only falls back to 3G/GPRS when Wi-Fi isn't available. This should work quite well for your email solution.
http://www.handywi.com/

SOURCE: "Packet Data Authentication Failed" what is

The error msg "packet data authentication failed" is displayed when connecting to internet via cell phone, even after having the original configuration settings provided by the supplier set to default. The problem can be solved by the following method or else contact the service provider. >Delete the old settings and then by switch off the phone. >Remove the sim card and reinsert it, after some time >gett the new settings and set it to default. Hope this helps. I had the same prblem. Even after calling cc, nothing helped. I tried all things but failed. Then unfortunately, i entered the url of the sp in the access point setting manually and wow it worked. I did this by using uninor.

SOURCE: nokia 6710 does not catch the wifi of my home but it shows other wifi network.but other mobile catches the network of wifi of home.

Your Nokia phone will see 802.11 b/g signals. Is your home access point broadcasting one of these?