Hi, My name is ***** ***** I will be helping you today. Can you tell me what type of wireless router you have? (you called it a modem)
In general, the range of a wireless connection is determined by the power strength of the router and can be impacted by interference by appliances and lighting. Be sure that the router is not stored in a cabinet or structure that has thick walls or is made of metal. Make sure there is no florescent lighting in the immediate area of the router (10 feet). Comcast uses proprietary routers which do not allow for much configuration by the consumer. You may have to contact them to make sure the signal strength is turned up.
Are you experiencing a week signal? or slow internet? You can check signal strength on your laptop by clicking on the icon on the lower right corner of your desktop and then clicking on the wireless network icon. you should see the strength indicated for each available connection. If it is above 2 then you should have adequate connectivity to your router and any latency might be on the internet itself. Any suspected internet issues should be reported to Comcast directly as they can run diagnostics on your service. If you are within 20 feet of your router and the connection is below 2 bars, then I would advise you contact Comcast to have them test your router. it may be defective.
You can also run a speed test here: http://www.speedtest.net
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