Did you know there are still people in the US who are connected to the internet via classic dial-up modems? They’re mostly older folks in remote areas without easy or affordable access to broadband, but they’re out there. And with the recent January 2026 update for Windows, Microsoft has played a nasty trick on such users.
After installing the January Windows 11 patch, dial-up modems may no longer work. As reported by Windows Central, the KB5074109 update has broken numerous modems in one fell swoop.
The most surprising thing about this, however, is that it isn’t a bug or a random error (as is the case with many other problems in this particular update). This move is entirely intentional. As Microsoft explains in the official release notes, the January update removes certain driver packages that the company considers “unsafe.” Allegedly, these packages contain unpatched security vulnerabilities and anyone who has such a modem should replace it with a new one.
Unfortunately, some old modems rely on these driver packages to continue functioning. Furthermore, this can also affect newly purchased modems, including those still available in the United States.
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Which modems are affected?
Complaints about malfunctioning modems are piling up on Microsoft forums and other sites like Tom’s Hardware. Many of these modems are apparently used in smaller companies, for example to answer phone calls or log systems.
No specific modem manufacturer stands out as especially affected. However, what is known is that the following driver packages were present before the update got rid of them:
- agrsm.sys (x86)
- agrsm64.sys (x64)
- smserial.sys (x86)
- smserl64.sys (x64)
To make matters even worse, the modems’ manufacturers apparently weren’t even informed that this would happen nor given enough of a heads-up to provide workarounds or fixes for users.
What can you do about it?
If you’re affected and you need to restore modem functionality, the only thing you can do right now is uninstall the KB5074109 update.
Learn more about how to roll back a Windows update. If you take this route, make sure you also disable automatic updates afterwards. However, please note that KB5074109 is a security update, which means you won’t be protected against current threats.