| SYSTEM INFORMATION | |
|---|---|
| OS type and version | Debian Linux 13 |
| Webmin version | 2.653 |
| Usermin version | 2.552 |
| Virtualmin version | 8.1.0 GPL |
| Theme version | 26.50.4 |
| Nginx version | 1.26.3 |
| Package updates | All installed packages are up to date |
Hi Virtualmin Team,
We have recently deployed a fresh production server running Debian 13 (Trixie) with Virtualmin installed using the LEMP bundle.
The NGINX package is the standard Debian 13 package:
nginx 1.26.3-3+deb13u7
nginx -V confirms that this build includes native HTTP/3 support:
--with-http_v3_module
We have successfully enabled HTTP/2 and HTTP/3 (QUIC) on one of our Virtualmin-managed domains, and HTTP/3 has been verified with curl --http3.
Verified HTTP/3 Result
HTTP/3 200
server: nginx
date: Thu, 20 Aug 2026 14:51:08 GMT
content-type: text/html; charset=UTF-8
alt-svc: h3=":443"; ma=86400
The server is also listening on UDP/443, and firewalld provides the http3 service:
http3
ports: 443/udp
Current Implementation
We are deliberately avoiding modifications to Virtualmin’s internal NGINX module/template files because these may potentially be replaced during future Virtualmin updates.
Instead, we are currently applying the HTTP/3 configuration directly to individual VirtualHost configuration files.
Because multiple VirtualHosts share the same IP address and TCP/UDP port, we are using reuseport only on the primary/default VirtualHost.
Primary/default VirtualHost:
listen 192.0.2.1:443 ssl default_server;
listen 192.0.2.1:443 quic reuseport;
http2 on;
Additional VirtualHosts:
listen 192.0.2.1:443 ssl;
listen 192.0.2.1:443 quic;
http2 on;
add_header Alt-Svc 'h3=":443"; ma=86400' always;
We understand that http2 on the listen directive is deprecated in newer NGINX versions (1.25.1+), so we intend to use the standalone directive:
http2 on;
rather than:
listen 443 ssl http2;
Questions Before Production Rollout
We would appreciate your guidance on the following points.
1. VirtualHost regeneration / configuration overwrites
If a VirtualHost is modified through Virtualmin — for example, changing SSL settings, Website Options, PHP settings, or other domain configuration — can Virtualmin regenerate the NGINX VirtualHost and remove manually added directives such as:
listen ... quic;
add_header Alt-Svc ...;
If so, which Virtualmin operations are known to trigger regeneration?
2. Recommended Virtualmin integration
Is there currently a supported mechanism, template variable, or Server Template option for the LEMP stack that allows Virtualmin to generate:
listen ... quic;
and/or:
add_header Alt-Svc 'h3=":443"; ma=86400' always;
automatically for newly created VirtualHosts?
If there is no official mechanism yet, is adding native HTTP/3/QUIC support to the Virtualmin NGINX integration planned?
3. reuseport handling
For multiple VirtualHosts sharing the same IP:443, is the following architecture recommended and fully supported by Virtualmin?
# Primary/default server
listen IP:443 ssl default_server;
listen IP:443 quic reuseport;
# Additional VirtualHosts
listen IP:443 ssl;
listen IP:443 quic;
Or does Virtualmin have a preferred way of handling the QUIC listener across multiple domains?
4. Firewall integration
Our Debian 13 installation uses firewalld, and the http3 service already provides:
443/udp
Are there any Virtualmin-specific firewall considerations when enabling HTTP/3/QUIC on a LEMP server?
5. Backup / restore and migration
Are there any known Virtualmin backup/restore or domain migration considerations for manually configured QUIC/HTTP/3 directives?
Why We Are Asking
We would like to standardize HTTP/3 across multiple Virtualmin-hosted domains, but we want to avoid implementing it in a way that conflicts with Virtualmin’s configuration management.
Our preference is to use the existing Virtualmin-generated VirtualHost configuration and make only minimal per-domain additions until native HTTP/3 support is available in Virtualmin.
We would appreciate confirmation that this approach is compatible with the current Virtualmin LEMP implementation, as well as any recommendations for a more integrated solution.
If HTTP/3/QUIC support is already planned for a future Virtualmin release, information about the expected implementation or roadmap would also be appreciated.
Best regards,
Hamed