I called my ISP and they fixed the problem. They said they didn't really know what was wrong but they "changed channels" (whatever that means) and it works fine now. RustyE, I don't have Comcast Modem. I have only this Cisco router/modem I mentioned before. The only difference I can see now on router's about-page is decrease of upstream power level from 52.5 to 45.5, so maybe there is something to it: Upstream Channels  Power Level:Channel 1: 45.5 dBmVChannel 2: 0.0 dBmVChannel 3: 0.0 dBmVChannel 4: 0.0 dBmV
I have a Wi-Fi connection problem on my Dell Inspiron 17R SE 7720 with Intel Centrino Wireless-N 2230. Every time after I log in to Windows I can’t use internet for about 5 to 15 minutes. After that time everything seems almost OK. During this time there’s yellow exclamation mark on my connection icon (saying that there’s no internet connection) just for a few seconds, than it dissapears and apparently internet connection is OK (signal strength is very good the whole time), but during this 5-15 minutes downtime I can’t use internet. Websites by domains don’t respond, neither pings do, but when I ping eg. google.com by its IP it responds quickly, so I thought it’s a DNS issue.Connection settings are automatic. DNS servers (resolved automatically) of my cable ISP respond OK when I ping them during the downtime. So just to check, I’ve set manually DNS servers to Google public DNS servers (both IPv4 and IPv6). It didn’t help.I don’t use antivirus software other than Windows Defender. The issue occurs with and without firewall. I have the most recent both BIOS (A11) and Wi-Fi drivers (15.3.1.2 downloaded from Intel site). My system: Windows 7 Home Premium PL 64bit. I keep the system updated with Windows Updates. The issue occurs when Windows manages my connection and also when I have Intel PROSet/Wireless WiFi software installed.I don’t allow Window to turn off the WiFi card (device’s energy settings). I’ve set Roaming Aggressiveness to 5. Highest and Ad Hoc Channel 802.11 b/g to 11 (I’ve seen such a piece of advice somewhere). Nothing seems to help.Maybe it’s something with compatibility with the router, by the issue doesn’t occur of any other device in my network (Android phones, Kindle, iPad). I’ve got Cisco EPC3925 from my cable ISP. They didn’t give me the password, so for now I can’t change its settings. Its “about” page reads:Cisco EPC3925 EuroDocsis 3.0 2-PORT Voice Gateway Model: Cisco EPC3925Vendor: CiscoHardware Revision: 1.0Bootloader Revision: 2.3.0_R1Current Software Revision: epc3925-E15-13-v302r125554-120725cFirmware Name: epc3925-E15-13-v302r125554-120725c.binFirmware Build Time: Jul 31 12:51:23 2012Cable Modem Status: OperationalWireless Network: EnableCable Modem State:DOCSIS Downstream Scanning: CompletedDOCSIS Ranging: CompletedDOCSIS DHCP: CompletedDOCSIS TFTP: CompletedDOCSIS Data Reg Complete: CompletedDOCSIS Privacy: DisabledDownstream Channels: Power Level: Signal to Noise Ratio:Channel 1: 5.9 dBmV 42.7 dBChannel 2: 6.7 dBmV 42.3 dBChannel 3: 6.4 dBmV 42.5 dBChannel 4: 6.2 dBmV 42.5 dBChannel 5: 6.0 dBmV 42.0 dBChannel 6: 5.5 dBmV 42.5 dBChannel 7: 0.0 dBmV 0.0 dBChannel 8: 0.0 dBmV 0.0 dBUpstream Channels  Power Level:Channel 1: 52.5 dBmVChannel 2: 0.0 dBmVChannel 3: 0.0 dBmVChannel 4: 0.0 dBmV
Connection (DNS?) problems on Inspiron 17R SE 7720 with Centrino Wireless-N 2230