Microsoft’s January 2026 Windows 11 update has unexpectedly disrupted internet access for a small but persistent group of users who still rely on dial-up modems. The update, identified as KB5074109, has been reported to disable modem functionality, particularly in remote and rural areas where broadband remains limited or unaffordable.
Unlike many recent Windows issues caused by bugs, this change appears to be intentional. In its official release notes, Microsoft says the update removes certain legacy driver packages it considers unsafe due to unresolved security vulnerabilities. While aimed at improving system protection, the move has left some older and even newly sold modems unable to function.
Reports from technology forums and outlets indicate that small businesses and niche users have also been affected, particularly those using modems for phone systems or legacy logging tools. The drivers removed include agrsm.sys, agrsm64.sys, smserial.sys, and smserl64.sys, which are required for a range of modem hardware to operate correctly.
Manufacturers were reportedly not given advance notice, limiting their ability to offer immediate fixes or updated drivers. For now, users who need modem access can only restore functionality by uninstalling the KB5074109 update and disabling automatic updates. However, doing so also removes important security protections included in the patch.
The situation highlights the tension between modern security standards and ongoing reliance on legacy hardware. While dial-up connections represent a tiny fraction of internet users today, the update underscores how system-wide changes can still have outsized effects on those who depend on older technology.
