I sometimes loose Internet connection to a wireless Broadband router .
Rebooting the router ie remove power and disconnecting/reconnecting at the pc always fixes it . No idea what causes it though
So if you've checked your wireless network and still get intermittent internet connections you need to look at the wiring.
It depends on the type of broadband service you are using, if it’s an ADSL broadband service the telephone line SNR (signal to noise ratio) can drop too low for the router to sync with the cards at the switch. The distance you are away from the ISP/BT exchange can play an important factor as can the quality of the line. If the ISP is trying to give you faster speeds over a degraded line it will occasionally drop below an acceptable SNR and will disconnect. Different makes of routers/ADSL modems have different SNR thresholds, some are better listeners. Also check any devices you might have hooked into your telephone sockets around the house, even line extensions that have been terminated badly can add noise to the line which will lower the SNR figure. If the disconnection is very frequent ask the provider to recheck you line and to monitor the drop out rate.
If it’s a Cable Broadband then it will either run though a setup box or a standalone modem, problems normally stem from a p1ss poor installation the signal rates are too high or too low and they have not used the correct attenuators or filters. Again call the provider and ask for a repair technician, they will normally swap or add a data filter or up/lower the signal levels.
Another option that can help you spot connection issues is to add 'Internet Gateway Device Discovery and Control Client' or 'UPnP User Interface' these are both part of the windows setup and can be found by going into control panel, double click add remove programs, select Add/Remove Windows Components, select Network Services and click details button, tick 'Internet Gateway Device Discovery and Control Client' and 'UPnP User Interface', click OK. You may need your windows disks.
Hope this helps....