I have a DLink D604T wireless modem. It has been working fine for the past 5 years but today the connection to my netbook computer kept dropping out.
I can fix it temporarily by going into Network Connections, right clicking the modem, selecting wireless networks, clicking the modem, going to properties and retyping the network password. I then have to set the firewal to advanced connection settings and typing in my family network password, and changing the Windows firewall settings from On to Off.
However, the connection drops out again after just a few minutes. If I then turn the firewall back on, it comes back on again for 5 minutes, but then drops out again. Then I have to repeat the whole process.
The strange thing is that when I go back to check the network password, the number of characters has changed each time. So I have to change it again. This seems to have started after a recent Windows auto upgrade of software, but I don't know if it is related. The problem is effecting on my netbook and none of the other computers in the house are effected.
I just removed the modem from preferred networks and added it again from scratch. Windows then promted me to provide the network key which I did. It has now stayed connected for the past 15 minutes! So it looks like all is well.