All of a sudden, unable to connect to internet

Question

I can get on the net, but after a while I get the message that I can't connect. I click on network diagnostics and the problem resolves itself. All is good for a bit but then suddenly the issue arises again. I may go for a few days without this issue cropping up, but then it may happen 3 times during a surfing session. This issue has only recently started happening. I know this description is vague, but any ideas? Thanks.

Answer 1

If your connection is Ethernet, and Network Diagnostics is flagging Ethernet and everything else all-red, check and make sure that the connecting cable isn't nicked or pinched and that the cable ends aren't loose (try jiggling them near the connector or gently pulling and see if the network connection goes up and down (flashes red or green on Ethernet status indicator on left side of Network Diagnostics) with your jiggling/tugging. If it does, replace the cable. The cable should never pull out the port without clicking the unlocking tab on the connector. Often this tab is bent and ineffective at locking the cable into the port firmly or is broken off. In either of those cases, replace the cable.
If your connection is AirPort, make sure you don't have a boat-load of too many competing networks operating in proximity of the computer. A symptom of this is the number of networks viewable by AirPort from the menu bar. Confirming collaborating info is when the alt key + menu drop down shows your airport speed keeps changing every time you click it up. If your connection is truly stable, speed changes will be rare or never and should be close to theoretical maximums for the class of WiFi connections you setup (B= ~12 Mbps max, G= ~56 Mbps max, etc).. You I recently was forced to wire my connections to the AirPort Extreme hub I use because there are like 8-11 networks popping up any time I check using the menu bar Airport status menu drop down (use it with alt key held for a LOT more useful info including signal strengths and throughput speeds). If there are too many competing networks, the chaos caused by all of the various networks with automated settings for rolling channels when they find too much signal interference causes a cascade of network instability for all of the networks as they each keep changing channels to try avoiding each other and everyone's network connections start suffering or collapsing as a result. If you have a wireless issue like this and don't want the tether of a wired connection, consider talking to your neighbors about changing all of their wireless settings off of automated channel selections and sit down and everyone decide to pick a particular channel and stick with it so everyone's network connections can remain stable and usable until the next idiot ads a new WiFi network again and everything starts collapsing as his network starts stomping on everyone else's channels looking for a less busy one... Did I say wireless *****?
If Network Diagnostics tells you that ONLY the ISP, Internet and/or server connection is failing, look further upstream at your connection from your home or office to the net ISP itself. If it is a phone company DSL connection, consider getting a more reliable service like FiOS or Cable modem if available as DSL is notoriously unreliable and may go down frequently / randomly if you are any good distance from the phone company switching office in your locale. Cable and FiOS are generally very stable connections with FiOS being the most stable and fastest of all connection types available to consumers. If it is the Server only that is failing, that can also be a problem at your ISP which your only resort is to switch ISPs if they are so incapable of providing reliable service....
The only other problem can be using too many net-connected applications at once with wrong settings for throttling in the apps. When I had cable modem service, I used to cripple my household network so no computers could load anything if I used a fast Mac running a bit torrent client and failed to throttle the upload speeds of the app. It would saturate the upload link, then all the other Macs weren't able to get through their URL requests uploaded to receive webpages back because their URL queries simply got drowned out by the sheer volume of data being pumped out by the bit torrent software and a lack of bandwidth available to get out further data. Lesson here: Watch your upload speeds if you start having trouble with download speeds.