Why Your VPN Connection Keeps Dropping—and How to Fix It

For many small to midsize businesses, a stable VPN is the hidden bridge between remote workers, branch offices, and your corporate backbone.

Imagine you’re a fast-casual restaurant chain with 15 locations, and your regional manager is locked out of your point-of-sale system because the VPN dropped yet again. Or, you’re overseeing multiple veterinary clinics that depend on a secure tunnel to the central database—but a broken VPN means delayed records, frustrated staff, and worried pet-owners.

When that tunnel keeps dropping, productivity and trust take a hit.

Below you’ll find a straightforward guide for IT professionals and network administrators to diagnose why a VPN connection keeps dying—and walk you through steps that help determine if it’s local, network-wide, or something in between.

Along the way you’ll see why working with a communications infrastructure partner like Fusion Connect, which offers robust connectivity, managed network services, and dedicated internet access, can simplify the fire-drill.

Check Bandwidth and Performance

One of the most common culprits for intermittent VPN drops is simply poor or inconsistent bandwidth. If the underlying internet link—whether branch office broadband, wireless backup or dedicated line—is fluctuating, the VPN tunnel may go down when it can’t maintain the handshake or keep the tunnel alive.

Example Scenario
Your 15-location restaurant deploys a VPN from each site into the datacenter. One location has a cable internet link showing 20 % packet loss intermittently—every time it happens the VPN drops. Replace or upgrade to a more business-grade link (perhaps via Fusion Connect’s dedicated internet access) and the drops stop.

Troubleshooting steps:

1. Run a consistent speed-test or throughput check on the site’s internet line while the VPN is active. Fusion Connect offers a free speed test for this very purpose.
2. Monitor for packet loss or high latency—VPN protocols often drop when latency spikes.

If you’re using a lower-tier link intended as “internet plus backup,” consider elevating to a managed service or Managed SD-WAN overlay offered by Fusion Connect for better reliability.

Review Firewall/Router/Policy Rules

Sometimes the issue isn’t throughput but firewall or routing rules—either because of newly added rules, changed policies, or a device reboot that resets defaults. A VPN may successfully connect but then get blocked or timed-out by a firewall that isn’t configured to maintain the session.

Example Scenario
A veterinary clinic location had a firewall firmware update that reset the NAT time-out to 5 minutes. The VPN would connect fine—but then after five minutes of idle it dropped, causing the application to freeze. Extending the time-out or enabling “keep-alive” policy fixed the issue.

Troubleshooting steps:

1. Check the firewall (or router) at the branch location: Are there rules blocking or limiting “tunnel keep-alive” traffic (e.g., IKE, IPSec, SSL VPN ports)?
2. Verify that NAT time-outs haven’t shortened and assume long idle times still keep the tunnel up.

If your VPN is part of a managed network service (such as the managed network offering from Fusion Connect), ask if the edge device configuration supports optimized tunnel persistence.

Look for DNS or IP Conflicts

Occasionally, the root cause is DNS conflicts or overlapping IP subnets, especially in distributed-office and branch-office environments. If two sites share the same subnet, or DNS resolves the VPN endpoint differently than expected, the tunnel can fail or flap.

Example Scenario
In the restaurant chain scenario, one location had been cloned from another and retained the same “10.0.0.0/24” LAN when the datacenter VPN expected a unique space. Every time that site reconnected it conflicted with routing and dropped. Renumbering the location’s LAN to “10.15.0.0/24” fixed the repeat drops.

Troubleshooting steps:

1. Check that branch offices and the datacenter (or cloud endpoint) do not share the same internal IP range—e.g., two “192.168.1.x” segments that collide.
2. On the client side, confirm the VPN endpoint hostname resolves to the correct public address. If it resolves to an old/failed service, the client may drop.

Use DNS-caching checks—clear local DNS cache, verify the correct public VPN endpoint appears, and ensure no stale entries.

Ensure the VPN Client Is Up-to-Date

Even in well-managed networks, a simple oversight—like an outdated VPN client or software bug—can cause instability. Many vendors release patches that fix tunnel negotiation issues, compatibility with OS updates, or edge-device handshake problems.

Example Scenario
After a Windows security update, one veterinary clinic’s laptops lost persistent connection to the VPN until the vendor’s client was updated. Once updated, the automatic reconnection feature resumed working.

Troubleshooting steps:

1. Check the version of the VPN client software on the remote device or branch router/edge. Compare with vendor’s latest release notes.
2. Look for user reportsstrong> of disconnects tied to specific versions (especially after OS updates).

In a managed network environment (like when leveraging Fusion Connect Managed Network Services), ask whether client updates and edge-device firmware are part of your support package—so you’re not chasing this manually.

Is it Local… or a Broader Outage?

After verifying the above, you still need to determine whether the problem exists at one branch or is infrastructure-wide (ISP issue, backbone failure, provider outage). Here’s how:

Troubleshooting Steps:

1. Check the internet link at the branch while disconnecting the VPN—if the branch still shows packet loss or outages, the issue is likely upstream.
2. Contact your internet provider/monitor status, or review the provider’s outage page.
3. If multiple branches served by the same provider are experiencing tunnel drops, chances are higher it’s an ISP or MPLS backbone issue.

When you work with a full-service provider like Fusion Connect — offering connectivity, managed network services, and dedicated internet access — you benefit from centralized monitoring and escalate paths through a single partner rather than finger-pointing across multiple vendors.

Final Thoughts

A VPN that keeps dropping can feel like a mystery. Systematically working through bandwidth, firewall/policy rules, DNS/subnet conflicts, client software and then ruling out infrastructure-wide outages will help you isolate and resolve the cause.

When you align with a partner who provides the underlying internet, the managed edge, and the service assurance—like Fusion Connect’s 100% US-based support team and unified connectivity stack—you free your team to focus on strategic value instead of the recurring “why did the VPN drop again?” cycle.

VPN Drop-Issue Diagnostic Checklist

Use this quick-reference guide to identify and resolve common causes of VPN instability. Brought to you by Fusion Connect — your partner in connectivity, managed network, and dedicated internet access.

Get the Diagnostic Checklist