VPN connection failures, which involve using modems of various telecom operators as a router, can be encountered quite often. One of the most common is error 734. Many users, trying to fix a problem that has arisen, sometimes do not even know which side to approach the resolution of the situation. But by and large, it is eliminated quite simply, for which you can apply several methods proposed in the material below.
What does VPN error 734 mean?
Before we take any action to correct this situation, let's take a quick look at why this failure occurs. The connection error message 734 clearly indicates that the link control protocol was interrupted for some reason (in our case, we are talking about PPPoE). Why did it happen so? It is believed that this is due only to the fact that the provider,providing a connection to its VPN server on the Internet, does not use encryption of transmitted and received data, while such settings are installed on the user's computer. That is why conflicts arise when connecting.
Only this reason the appearance of error 734 is not limited. Quite often it can be found when using special Cisco VPN Client software. Only in this case is it reported that a failure has occurred and the application will be closed. To restore the connection parameters, you can use a few simple tips, which are offered for consideration.
How to fix PPPoE error 734 in the easiest way?
So, if the failure arose, so to speak, out of nowhere (before it appeared, everything worked), it is quite possible that the cause could be short-term, not particularly critical failures of the operating system itself.

In this case, you can simply try to restore the system by selecting the point before the error occurred during the rollback. If this does not help and error 734 appears again, it may very well be that some kind of virus has entered the system blocking the connection.

The easiest solution would be to scan your computer for threats using some kind of portable scanner or disk programs like Rescue Disk, from which you can boot even before the operating system itself starts.
But sometimes everything can be fine with system errors, and virusesnot on the computer either. What to do in such a situation?

Here you will have to go through the "Control Panel" to the section for managing networks and sharing, then use the item to change network adapter options, and then through the properties item, move to the settings tab and click the "PPP Settings …" button. After the settings window appears with three items, check the very first one (enable LCD extensions), save the settings and try to connect again.
Additional security steps
However, it also happens that the above proposed variant of actions to correct error 734 does not work. In this case, you can offer another additional option for settings.

In the same main window shown above, go to the security tab, and then select "Optional" in the data encryption drop-down list (with connection even without encryption). Again, save the settings and connect to the VPN server again.
Cisco VPN Client Error Correction Options
Now a few words about the issues with the Cisco VPN software client. To fix such problems, you can first use System Restore and a virus scan. However, if this does not work, many experts recommend checking or repairing the registry, for which you can use utilities like WinTruster. AlsoIt would be useful to clean the computer from "garbage" (all kinds of temporary files) using any optimizer or cleaner like CCleaner or ASC. Finally, if the problem persists, completely uninstall the client from your computer, and then reinstall it. To uninstall, use not system tools, but uninstallers (for example, iObit Uninstaller). If, after all the above steps, client-related errors reappear, update the network drivers using automated programs (Driver Booster), which are best suited for such operations.
What to do if all else fails?
Finally, do not forget that the occurrence of failures associated with a VPN connection may not always depend solely on the settings of user computer terminals or laptops. On the part of the provider, their appearance cannot be ruled out either. Contact your ISP or carrier support. It is quite possible that specialists will solve your problem (in extreme cases, maybe they will at least tell you what can be done to eliminate failures). If the failure is short-lived and is associated solely with technical work, you will not need to do anything at all, and after the maintenance is completed, the connection will work again anyway.