Managing VPN Certificates on Synology NAS

How to manage VPN certificates on Synology: renew, update, and secure

In recent years, secure remote access has become very important. Synology’s VPN Server encrypts your network connection, whether you need to support hybrid teams, manage IT from afar, or access files securely. But if you don’t take care of your certificates, even the safest VPN setup can fail.

One of the most common reasons for VPN outages is certificates that have expired or are set up wrong. If you take care of them, they will keep encrypting your data and stop users from getting connection errors.

Why VPN Certificates Are Important

VPN certificates prove the identity of both the server and, in some cases, the client. They make sure:

Communication that is encrypted
Checking someone’s identity
Keeping man-in-the-middle attacks from happening
Safe key exchange

Clients may not be able to connect if a certificate has expired. If it is set up wrong, the strength of the encryption may go down or warnings may show up.

Certificate hygiene is no longer optional in 2025 because people are paying more attention to cybersecurity.

Learning about the different types of Synology VPN certificates

Synology VPN Server often uses certificates in three different ways:

Certificates for OpenVPN
Setting up L2TP/IPSec pre-shared keys
SSL certificates that are connected to DSM

OpenVPN usually uses server certificates that are made in-house or given out by a trusted Certificate Authority (CA). If these expire or are replaced without updating client profiles, remote connections will not work.

You can also manage certificates from one place in DSM by going to Control Panel > Security > Certificate.

How to Find Out When a Certificate Expires

Check the validity of your certificates on a regular basis to avoid downtime:

Sign in to DSM
Go to the Control Panel
Choose Security
Click on the Certificate tab

You will see expiration dates and services that have been assigned here. If your VPN is linked to a certain certificate, check to see if it has been renewed before the expiration date.

Setting reminders or calendar alerts stops things from going wrong.

How to Renew Let’s Encrypt Certificates

If your Synology VPN uses a Let’s Encrypt certificate, it will usually renew itself. But failures can happen because of:

Wrong DNS settings
Port 80 or 443 is blocked
Firewall rules
Errors in domain validation

To renew by hand:

Go to the DSM Certificate
Choose the certificate for Let’s Encrypt
Click on “Renew”

Make sure that the internet can still reach your NAS while it is being validated.

Updating OpenVPN Profiles After They Expire

Users may need new OpenVPN configuration files after renewing or replacing their certificates.

The steps are:

From VPN Server, export a new .ovpn file
Securely share updated profiles again
Change the old certificates in the client configuration

Even if the server certificate is valid, not updating client profiles can cause connections to fail.

Making VPN Security Stronger

In addition to renewal, think about these modern best practices:

Set up strong encryption settings
Turn off old protocols
Turn on firewall restrictions
Use two-factor authentication
Limit VPN access by IP range

Certificates keep encryption safe, but layered security makes the whole remote access system stronger.

Common Problems with Certificates and How to Fix Them

VPN connects, but it gives a warning: “Check certificate trust chain and CA validity.”
Let’s Encrypt renewal fails: Check your DNS records and make sure your ports aren’t blocked.
Clients can’t connect after renewal: Re-export and reinstall VPN profiles that have been updated.
Errors due to certificate mismatch: Make sure that the DSM service assignment matches the VPN service.
Regular checks stop these problems from getting worse and causing big outages.

Security Benefits for Synology

The introduction of DSM 7 brought better certificate management and more accurate service mapping. You can give certificates to each service to make sure that the correct encryption keys are used by VPN, DSM, and reverse proxy endpoints.

When set up correctly, Synology provides a strong security base with firewall rules, account protection, and snapshot backups.

About Epis Technology

Epis Technology helps businesses set up secure VPN networks that work with firewall rules, hybrid cloud backup, and identity management. The team checks the lifecycles of certificates, automates renewal monitoring, and makes sure that remote access meets Microsoft 365 security standards. Businesses lower the risk of downtime and unauthorized access related to certificates by combining VPN deployment with their overall disaster recovery and monitoring plans.