Big Sur VPN Issues?
Common Problems and Fixes
Key Takeaways
Big Sur changed how VPNs work—Network Extensions replaced Kernel Extensions
Many VPN issues stem from outdated clients that don't support the new APIs
Most issues are resolved by updating VPN client to a Big Sur-compatible version
What Changed in Big Sur for VPNs
macOS 11 Big Sur introduced major architectural changes that affected VPN compatibility. Understanding these changes helps explain why your VPN may have stopped working.
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Kernel Extensions (KEXTs) deprecated in favor of Network Extensions
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New security requirements for system extensions
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Changes to how apps interact with network stack
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ContentFilterExclusionList (Apple apps bypassing VPN)
Common Big Sur VPN Issues
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VPN client won't install or crashes
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"System Extension Blocked" errors
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VPN connects but no traffic flows
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Apple apps bypass VPN unexpectedly
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DNS resolution fails while connected
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Slow VPN performance
The Network Extension Transition
Before Big Sur, VPNs used Kernel Extensions (KEXTs) that ran with high privileges in the macOS kernel. Apple deprecated these for security reasons.
New VPNs use Network Extensions—sandboxed, more secure, but requiring vendors to rewrite their software. Many VPN vendors were slow to adapt.
If your VPN worked before Big Sur and stopped after upgrading, an outdated client is likely the cause.
Fixing "System Extension Blocked"
Open System Preferences → Security & Privacy
Click the lock icon and authenticate
Look for message about blocked system extension
Click "Allow" next to your VPN
Restart your Mac
Try connecting to VPN again
Apple Apps Bypassing VPN
Early Big Sur versions had a ContentFilterExclusionList that let Apple apps bypass VPNs and firewalls. This was controversial and partially addressed in later updates.
Update to Big Sur 11.4 or later to get fixes for the ContentFilterExclusionList issue.
Fixing DNS Issues
VPN may connect but fail to resolve domain names. Check your DNS configuration:
# Check current DNS servers
scutil --dns | grep nameserver
# If empty or wrong, VPN didn't set DNS correctlyYou may need to manually set DNS or update to a VPN client version that handles Big Sur DNS properly.
Updating Your VPN Client
Most Big Sur VPN issues are solved by updating to a compatible client version:
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Cisco AnyConnect: Version 4.9 or later
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GlobalProtect: Version 5.1 or later
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OpenVPN Connect: Version 3.2 or later
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Tunnelblick: Version 3.8.4 or later
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WireGuard: Native macOS app (built for Big Sur)
Remove the old VPN version completely before installing the update. Leftover kernel extensions can cause conflicts.
When VPN Updates Aren't Enough
Sometimes updating the VPN client isn't possible—corporate VPNs are controlled by IT, and they may be slow to push updates.
Options if you're stuck:
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Request IT update the VPN client deployment
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Check if a newer client is available for manual install
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Consider upgrading to macOS 13.5+ for better VPN compatibility
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Use SplitTunnel on macOS 13.5+ for per-app VPN control
Considering macOS Monterey or Later
macOS 12 (Monterey) and later refined the Network Extension APIs, improving VPN compatibility. If you're still on Big Sur and facing persistent VPN issues, upgrading may help.
On macOS 13.5+, SplitTunnel provides per-app VPN control using Apple's modern Network Extension framework—letting you route specific apps through or around your VPN.
Frequently Asked Questions
Per-App VPN on macOS 13.5+
Upgrade to Ventura or later and get full per-app VPN control with SplitTunnel.
Requires macOS 13.5 (Ventura) or later