[gambatte]

Have you ever done any intervention to connect your network at all or just turned the WIFI on and let 'er rip? Usually, when you connect your network by viewing your available networks, tap and hold yours, and select connect, it will connect to that one until your change it to another. That is of course if you are in range. Also, is your network secured? You will have to input the encryption key but sounds like you can connect OK 20% of the time.