Proton VPN 5.1.9 targets Windows split-tunneling reconnect bugs

Cover: AI-generated editorial illustration, not an event photograph or product screenshot.

Proton VPN’s Windows release notes list version 5.1.9, dated 29 October 2026, with fixes for split-tunneling behavior after reconnecting. Proton says the update addresses exclude-mode filters being removed during reconnection and inconsistent split-tunneling behavior afterward. It also lists improved recovery after temporary service disruptions, issue-report validation changes, an OpenVPN library update to 2.6.23 and minor security improvements.

This is a follow-up on that 29 October release, not a new release announced today. The notes do not establish how many users encountered the problems, identify a specific exploited vulnerability or prove that every routing scenario now behaves correctly. VPNBlade has not installed the update, reproduced the bugs or performed a packet-level test. The practical implication is narrower: Windows users relying on routing exceptions have a concrete reason to check their installed version and review their intended behavior after an update.

Why a reconnect fix deserves attention

Split tunneling deliberately sends different traffic along different paths. That makes the meaning of a working connection more specific than “the VPN connected.” A user may expect a selected application to stay outside the tunnel while another uses it. If the actual routing no longer matches that expectation after a reconnect, the user can experience a functional problem even though the main status indicator looks normal.

The release notes give a reason to include reconnection in a post-update check, rather than verifying only the first successful connection. They do not tell us the direction, duration or privacy consequence of every affected session. We therefore do not label this a confirmed data leak or tell readers that their previous traffic was exposed. Those conclusions would require evidence beyond a brief vendor change log.

Establish what your Windows configuration is intended to do

Proton’s current Windows split-tunneling help distinguishes Exclude mode, which leaves selected applications or IP addresses outside the tunnel, from Include mode, which puts only selected applications or IP addresses inside it. The documented controls allow choosing application executables and IP rules. Changes require applying the configuration or reconnecting, depending on the current connection state.

Write the intended rule in plain language before checking behavior. For example, “this personal application should use the VPN, while this local task follows its documented exception” is more useful than a screenshot of several checked boxes with no explanation. This is an illustrative requirement, not a configuration we tested or a recommendation to exempt sensitive traffic.

Our Windows split-tunneling guide explains how to keep app selection, route expectations and verification separate. A small acceptance checklist is easier to interpret than changing several unrelated options after every failure.

Use the documented update route

Proton’s update instructions place the Windows version and update check under Settings, Support and About. The provider says users receive update notifications and can select Update when one is available. This is a description of the documented workflow; we have not updated a reader’s device or confirmed availability for a particular installation.

On an organization-managed computer, use the organization’s approved update process. Keep the installed version, relevant configuration and any error message in the support record. Do not download a replacement client from a search advertisement or weaken certificate or endpoint protections to make an unfamiliar installer run.

Once the update is complete, check the version actually shown by the application. An installer download, an update notification and a running updated process are different observations. If the expected version is not visible, ask the provider or administrator to resolve that discrepancy before interpreting a routing check as a test of the new release.

Split tunneling and kill switch are related but different

Proton’s split-tunneling documentation specifically says Windows supports using either its Standard or Advanced kill switch with split tunneling, unlike the general incompatibility it describes on most other platforms. Keep the Windows qualification attached to that statement. A Windows release is not evidence that the same interaction changed on macOS, Linux or a phone.

The provider’s kill-switch help distinguishes Standard behavior after an accidental drop from Advanced behavior that permits access only while connected. Those descriptions explain intended product behavior; they are not results independently verified by VPNBlade. A deliberate disconnect is also a different event from an unexpected interruption. Do not assume that one observation establishes all failure cases.

Review the intended combination without disabling a protection as a troubleshooting shortcut. Our kill-switch guide provides background, and the connection-check guide separates a status indicator from evidence about a particular traffic path.

A released fix is not the whole roadmap

Proton’s 21 October fall-and-winter roadmap discusses future work including pause-and-resume controls and further kill-switch improvements. Those plans are separate from the items actually listed for Windows 5.1.9. We have not treated a roadmap feature as shipped merely because it appears on the same provider’s website.

This distinction is useful when deciding whether an update addresses your requirement. Start with the release notes for your installed platform and version. If the feature you need is described only as planned, preserve that uncertainty rather than assuming the latest version contains it.

What to report if behavior remains inconsistent

Record the app version, Windows version, selected routing mode, affected application and the sequence leading to the problem. Explain whether it appears on initial connection, only after a reconnect or only for one task. Share logs through the provider’s official support process and review them for private information before posting anything publicly.

A fix announcement is a reason to update and review a relevant configuration, not a reason to buy a new subscription. Proton documents split tunneling as a paid-plan feature; existing users should establish their actual entitlement before purchasing anything. Readers comparing plans can use the Proton VPN assessment and inherited offer below, which is not a guarantee of routing reliability or evidence that a paid upgrade is needed to install this release.

The useful result is a current supported installation with observed behavior that matches a written routing requirement. If those do not match, the specific record gives support something concrete to investigate.

Cover: AI-generated editorial illustration, not an actual Proton application, device test or security incident.