An error occurred while Internet Connection Sharing was being enabled (null)

So, I use Internet Connection Sharing to connect my PC to the internet via my laptop, since all wireless nics I've tried on my PC suffer from frequent packet loss while my laptop is fine, and my living situation doesn't allow me to connected wired.

The problem started only recently, and it had been running fine for months beforehand. I have checked all the services listed on various websites when I google the error message. They're running. Yes, this includes Windows Firewall. Yes, I set the LAN connection on both computers to find IP address by default. Yes, I have a second connection I'm trying to share on one of the computers. Yes I've tried restarting the computer. Both of them. Especially the one having the error.

Nothing is working. This is very frustrating.

"Yes, I have a second connection I'm trying to share on one of the computers."

This statement in particular is a bit confusing. Are both PC's connecting to the laptop, and the laptop is the host for your internet, or are you trying to daisy-chain laptop-> PC1->PC2? Ideally, your laptop should be setup to work as a router, with an ethernet line to a hub/switch that the PC's connect to with ethernet.

If that is your topology where your laptop is setup as the central router, then it may be an issue with firewall or port forwarding. If you forwarded ports to PC1, all data is likely being sent to that PC1 and none to PC2. Port forwarding shouldn't really be needed with the latest implementations of NAT--that should really only be used as a troubleshooting step to isolate an issue with ports being blocked. You may need to set a rule to enable/allow the ports to all IP's, as it can become problematic when you lock them down as a forward to one specific IP when you need it to go to other IP's as well.

You may fair better to get a wireless router and set it up as an access point to your internet source. This may streamline things much more in regards to performance, configuration complexity, as well as energy consumption.

What I'm doing is having my PC wired to my laptop via an ethernet cable, and the laptop wirelessly connected to the internet. As I mentioned in my first post, I am doing this because my PC inexplicably doesn't like using wireless: It'll keep dropping packets so every so often I'll get a second or two of everything freezing. This does not occur when I have ICS set up. So, yes, I have a router, but with my PC wirelessly connected to it FFXIV is damn near unplayable.

As for the suggestion about port forwarding, the problem is I can no longer set up ICS in the first place! I get the error message this thread is named after when I attempt to turn it on.

So, hey, alternate question: Any idea why a PC would routinely drop packets over wireless, when a laptop in the same area does not? The result is the same over three different wireless USB NICs tried in various USB slots, as well as a wireless NIC card slotted into the motherboard.

ah... so you can't get ICS service to start... sorry.. misunderstood where your problem was originating. Sorry, not much help with ICS... haven't tinkered with it since the Win2000 Server days. Can tell you that a lot of times I had issues with RAS not starting properly. Could load services.msc to see if your Remote Access services are starting properly...names have likely changed, but you should see one or two that reference it. Could also be a protocol support that is knackered up as well. Could try to reset some of them. Here's two commands I've had to use a lot in Windows over the years:

netsh winsock reset
netsh int tcp reset c:\tcpreset.log

IPV6 is coming into play now too, that could be causing some weirdness if the protocol isn't enabled/supported well across the interfaces.

As for the wireless for the PC... wifi has often been a fickle beast. A/B/G/N and the new AC adaptions just make a muddled mess, especially if you are running a mixed environment. May be a lot of noise on one band because of all the crowding in the channels available depending on which protocols are in play. Try disabling the broadcast protocols you don't need and such (should be able to set it to just G or N if that's all you are using). Maybe switch the broadcast channel the router is using also. Not uncommon to see a lot of devices broadcasting on the same channel because so many people just leave it at the defaults--all that crosstalk can wreak havoc sometimes. Some have options for adjusting the power/sensitivity of the radio/antennae as well--may help with fine-tuning a bit.

Could try an USB extension cable for the dongle too... provided you are using a USB wifi dongle. Hope it isn't a drop-in card. Those never set well with me. Sticking the antennae at the back of the PC, which typically gets crammed under a desk or in a corner with the antennae up against the wall. Just messes up the path to the router in a major way. Free-standing antennas that you can screw on to those cards can get pricey too--but a standard USB extension cable is usually kind of cheap, and may be long enough to stick the dongle up on the desktop or something. You may even have one laying around somewhere.

I've switched to a multi-band (AC 1900 with MIMO and 3 external antennas) router at the house because my old 54G was acting up with the 3 rokus, 2 laptops, 2 phones, PS3, and blu-ray running on it. Condo complex with a LOT of crowding. Since upgrading and running purely Wireless-N for the Rokus and phones, Wireless-AC for the laptops, and routed ethernet cables for the PS3 and Blu-Ray, it's solid once again. Think the trick was getting away from the rigid 54G bands-- the -N and -AC have a little more width per channel to play with I guess to get a better lock. It wasn't cheap... Asus RT-AC66R set me back $175, but the difference it has made in my video streaming is incredible--not to mention I no longer see the 10+ms lag across the wifi when I trace now.

Oh.. an afterthought. If you are using a third party firewall on that PC, it could be a source of injected lag or other weirdness causing issues. Discovered that a while back with Zonealarm--used to be a much thinner, friendlier app, but it has gone the way of Winblows and gotten considerably bloated. AVG has been known to be problematic as well for some. Anti-Virus is starting to suffer from this as well.. might have to drop Avast if they don't reign it in soon. Found an interesting front-end for managing the Windows Firewall called Tiny Firewall (can get it from cnet and pcmag downloads). There's a trick to using it though. It doesn't notify you when something is blocked (everything is blocked at first) so you have to either "train" it by toggling the learning mode while launching an app, or go in and manually add rules. But, it makes managing the built-in Windows firewall a lot less intimidating, and doesn't bog the networking layer nearly as much as some 3rd party ones do.

I've tried both of those commands, with no result, and all related services and their dependencies are active and running. IPv6 does seem to be the issue though. When I get that error message, there's an alert in my event log that says it was unable to allocate memory for IPv6... despite having at least half my RAM available, and surely enough virtual memory on top of that.

I'll keep that in mind, though I don't have much money to splurge on upgrades at the moment.

Also, I'm not running any third party firewalls on either computer. I've already read elsewhere that Windows Firewall needs to be running for whatever reason, so I've got that running.