SSL-VPN outage or weak connection

Good afternoon — just sharing some general troubleshooting insight.

Issues like intermittent VPN disconnects or unstable connections are usually caused by a combination of factors, not just one single issue.

A few common areas to check:

1. Client-side connectivity

• Many VPN drops are related to unstable user internet (WiFi, ISP issues, high latency)
• Try testing from a different network to compare

2. FortiGate resource usage

• Check CPU and memory during peak hours
• High load can impact SSL VPN stability

3. SSL VPN configuration

• Verify session timeout settings
• Check if DTLS is enabled (can improve stability/performance)
• Review logs for disconnect reasons

4. Software versions

• Ensure FortiClient and FortiOS versions are compatible
• Some versions are known to have stability issues

5. Logs & debugging

• Check VPN event logs on FortiGate
• Look for patterns (timeout, negotiation failure, etc.)

If possible, try to identify:

• Does it happen to all users or only some?
• Does it occur at specific times?
• Are users on the same ISP/network?

That usually helps narrow down whether it’s client-side, network-related, or firewall-related.

Hope this helps as a starting point — others may have more specific input depending on your setup.

Hi Charly

Such issue can be caused by Internet connection instability or saturation. It is not the unique possible issue but is the most common.