There are a number of problems that can lead to devices dropping off a Connectify Hotspot. It may mean that the Hotspot itself is having some kind of trouble, but it can just as easily mean that your devices are just not able to "hear" the Hotspot. That's particularly likely if, all of a sudden, you start to have problems where none occurred before. It may be interference with another radio source. Or you may be running into problems with over-aggressive power management or hidden driver problems that stop your Wi-Fi from functioning without necessarily communicating with Connectify Hotspot that this is happening.
Radio Fading and Interference
Wi-Fi is by its nature a two-way radio, and just as with an FM radio or a cellular phone call, signals can fade or be drowned out by something else. Imagine you and a friend travel to Citizen's Bank Park, and get to hang out on the ball-field for while. You stand at home plate, your buddy starts walking toward the outfield. You have to shout louder as your buddy moves away, he's got to shout louder back at you. Eventually, you can't hear each other. Wi-Fi devices have the same problem. A PC makes a decent virtual router or Wi-Fi hotspot; most can transmit at 100mW or so, which was a fairly standard power level for a dedicated router, at least a few years back. But the PC's antennas may not be a good as a dedicated router's, or the antennas may be fewer in number. Dropping signals a few rooms away from your PC is a normal occurrence. The device cannot "yell" loud enough for the PC to hear it.
So, back at the park, you're having a conversation with your buddy; you're still on home plate, he's moved to the pitcher's mound, and it's working fine. But now a rowdy gang of old-timers comes out to the ball-field, and they're kind of hanging around where you are. Your buddy is still talking or shouting just as he was before, but these old guys are so loud, his voice is drowned out. That's an interference problem, and Wi-Fi devices that suddenly drop off a previously functioning Connectify Hotspot may have just had a very similar kind of problem.
There are no natural sources of radio noise in the Wi-Fi band, but there are plenty of man-made sources. If you have a microwave oven in the house, it's using the same 2400MHz band as your Wi-Fi, and might cause interference. Some types of cordless phones, game consoles (particularly the X-Box 360), some television video senders, etc. all use this band, because unlike most radio bands, it doesn't require a license. And the most likely source of all: other Wi-Fi devices can interfere with Connectify Hotspot.
The Wi-Fi Channel Conundrum
You may have looked a bit at how Wi-Fi channels are set up. Everyone knows the basic idea of a channel; they are used for television, for radio, and though you can't see it, for cell phones and cordless phones, too. Consider the following graph:
The graph was created by the Wifi Analyzer app for Android (a handy tool when searching for sources of interference). It represents the wireless signals in and around the Connectify offices; a number of staff members are currently working off the Connectify Hotspot called "TheDude!". You can see Wi-Fi's dirty little not-so-secret here. While there are 14 channels shown (channel 14 isn't used in the USA), each Wi-Fi hotspots actually consumes five channels. There are hotspots clustered around channels 1, 6, and 11, because these are the three totally clear channels in the band. That's correct: There are really only three separate channels on Wi-Fi.
With that said, the Wi-Fi protocols are very clever, and immune to some interference. Devices here in the office have absolutely no problem connecting to "TheDude!", even with all those other hotspots also on channel 11. However, connecting to the "Connectify" hotspot down the hall instead might be more difficuly. And forget about connecting to the rug shop's hotspot.
Hopefully, most Connectify Hotspot users don't see this much Wi-Fi traffic. But you never know. You might be using your PC as a hotspot for months, then all of a sudden you have a powerful hotspot from next door drowning out the signal between your PC and your other devices. Some more modern, dedicated routers can put out 250-500mW of power, which can mean that they seem much louder to some of your devices than your PC might, depending on conditions. That can lead to devices that start connected, but drop off and might not reconnect very easily.
If you're monitoring Wi-Fi with a tool like this, you might be able to fix your problem simply by moving things around. Maybe the neighbor's Wi-Fi isn't all that powerful, but it's still blocking Connectify's hotspot in the places you like to use your portable devices. It could be that moving the PC, or even the Wi-Fi antennas on the PC, will fix this problem. If you're using a USB dongle for Wi-Fi, try moving the dongle to a better location, maybe up high with an extension cable. If you're using built-in laptop Wi-Fi, try moving the laptop around a bit, and keep the lid open -- most laptops these days have their Wi-Fi antennas on either side of the screen.
We don't currently have a way to change the Wi-Fi channel from within Connectify Hotspot. Some of this is the history of Connectify Hotspot and Windows. Until Windows 7, Windows always considered Wi-Fi as something to which it connects. It never had much to consider about the channel to use, except in the rare case of Ad-Hoc networks. Windows always starts with the last Wi-Fi channel used, and that's no different when starting Connectify Hotspot. Connectify Hotspot will use the WIndows default channel, which cannot be directly set by the user.
While it is useful to have a tool that helps find some better location to put Connectify Hotspot, the question is how to get it there? There are a couple of work-arounds. One is simply to connect the PC to that channel somewhere else: office, coffee shop, friend's house, etc. The next time Connectify starts up, it will use that new default channel, and avoid the loud neighboring router.
Another possibility is changing some of your network driver's settings. USE THIS WITH CAUTION. YOU CAN ABSOLUTELY BRING ON THE BLUE SCREEN OF DEATH OR SCREW UP YOUR WI-FI SETTINGS. In fact, this article was written twice for just that reason. If you try this, save your work, close every other program, and prepare for the possibility of a crash. This task isn't to be undertaken lightly -- we recommend exhausting other possibilities first, but it wouldn't be fair to say "change the channel" and then proceed to say it's impossible to do so.
As illustrated above, start the Windows Device Manager and find the Wi-Fi device. It's safer if you now disable this device (from the right-mouse-click menu), and wait a minute or two for it to stop. Next, select "Preferences" and then pick the "Advanced" tab. Make sure if you change any settings, that you write down the setting you changed, and what the original value was. If you don't understand the name of the setting, don't use it. You may get some help on these settings in the user manual for your Wi-Fi card as well. And after you make a change, don't forget to re-enable the driver.
The settings here are totally up to your device manufacturer -- and you may have different ones. What I did seemed pretty safe (until the BSOD): I set the Ad Hoc channel to Channel 3. When I restarted Connectify Hotspot, there were no changes. "TheDude!" was still on channel 11. I then changed the Connectify Hotspot setup to use Ad-Hoc, and sure enough, I got channel 3. Of course, my Android phone will not talk to an Ad-Hoc network, so I changed back to Access Point mode, and got channel 1. Go figure. It probably means that Windows reset the default for this device. In any case, some drivers have ways to restrict the channels in use, others have features like the one in this example. Use at your own risk, but this is a way to sometimes move the Connectify Hotspot channel.
And finally, there's the human engineering solution. If that neighbor just put in a big, loud hotspot that's drowning out your Connectify hotspot, see if you can get them to change their channel. Never underestimate the power of a six-pack or a bottle of wine.
Power Management 1, Hotspot 0
The next cause of odd device disconnects is power management. If you are running an older version of Connectify Hotspot, get the very latest version available. Connectify Hotspot has some ways of at least suggesting to a Wi-Fi device that it should not power off when it thinks it is not needed. But some devices do not necessarily listen that well. If you see a pretty regular time, perhaps 15 minutes or a half-hour of great Connectify Hotspot functionality, then things just stop working, that could be your tablet or phone going to sleep, but it could also be your PC's Wi-Fi card.
Along with the latest release of Connectify Hotspot, you can adjust power management on your PC. Many Wi-Fi drivers have their own setting, which you get to via the Device Manager, just as before. This is usually a check mark: if your driver has a "Allow the computer to turn off this device to save power" option, make sure it's not checked. If you still have problems, try turning off power management entirely, and see if that solves the problem. If so, you may have to dig deeper into power management options; if not, on to the next possibility.
That Old Rusty Driver
Another possible cause of your devices falling off the Connectify Hotspot network is simply Connectify Hotspot coming down. If it's a Connectify Hotspot internal problem or something else that Connecitfy Hotspot can detect, it will to show up as a pop-up notification of some kind on your PC. If several devices all drop off at the same time, first thing to do is check the PC for any sign that Connectify Hotspot itself knows about a problem.
However, there are occasional problems that Connectify Hotspot doesn't detect. Again, if you are having problems, the first thing to do is update Connectify Hotspot. Each new version fixes old bugs we know about, some of which might be in Connectify Hotspot itself, but some of which may be the result of Windows misbehaving. We cannot always fix such problems, but Connectify "learning" about some problems will make them effectively vanish.
One class of hotspot failures that do not always show up are partial driver crashes. If a network driver crashes entirely, Connectify Hotspot will see the device go away or, worst-case, your PC will crash. Either way, the problem is rather obvious. But there have been some cases in which only part of the driver stops working. For example, it may still be responding to Connectify Hotspot, but broken in the other direction, so device activity on your Hotspot never gets seen by Connectify Hotspot. In the cases seen so far, the culprit has always been old network drivers.
Many users are still running their Wi-Fi cards with network drivers that were released even before Windows 7 shipped. For plain old Wi-Fi operations, that's probably not a problem, since Wi-Fi client mode has been working on Windows for over a decade. But the other piece, the hosted networking support that allows Connectify Hotspot to build an Access Point, is relatively new, and it was all but untested before Windows 7's release. We recommend anyone that has mysterious connection losses to follow the other suggestions here, but also to update their drivers. We have written an article on this topic here: Updating Your Wireless Drivers. We also have a list of known-good and known-problem devices, including links to some of the driver updates in the article Is My Wi-Fi Card Supported?