Requirements and Network Architecture

Hardware and system requirements

Before installing Viaalink Relay, ensure your host machine meets the following platform and system specifications:

Domain and DNS requirements

Viaalink Relay requires a domain name you control (for example example.com). To route incoming traffic and issue automatic wildcard certificates via Let’s Encrypt, configure two DNS records:

1. Host record (relay.example.com) — points to your Relay server’s public IP address.
2. Wildcard record (*.relay.example.com) — directs all dynamically generated subdomains (such as app.relay.example.com) to your Relay.

Static public IP (A and AAAA records)

If your ISP or hosting provider provides a static IPv4 address (and optionally IPv6), create direct address records:

relay.example.com.    300 IN A    203.0.113.10
*.relay.example.com.  300 IN A    203.0.113.10
relay.example.com.    300 IN AAAA 2001:db8::10
*.relay.example.com.  300 IN AAAA 2001:db8::10

Dynamic IP (CNAME records)

If you run Viaalink Relay on a home connection or NAS with dynamic IP tracking (such as ASUSTOR EZ-Connect yourname.myasustor.com), point both host and wildcard records using CNAME:

relay.example.com.    300 IN CNAME yourname.myasustor.com.
*.relay.example.com.  300 IN CNAME yourname.myasustor.com.

Important: If you manage your DNS with Cloudflare, set both records to DNS only (grey cloud). Proxied records (orange cloud) intercept inbound traffic at Cloudflare’s edge and break on-demand Let’s Encrypt TLS validation.

Port reference table

The following table lists every port used by Viaalink Relay, whether it requires external router forwarding, and its purpose:

Router port forwarding: UPnP vs manual rules

To make your published addresses accessible outside your local network, your router must route incoming traffic to your Relay server.

Automatic forwarding (UPnP and EZ-Router)

Viaalink Relay can automatically request port mappings from your router using standard Universal Plug and Play (UPnP) or ASUSTOR’s native EZ-Router service:

• High ports (2222, 3478, and 28080 on ASUSTOR only): Most consumer routers permit UPnP mappings for ports above 1024 without administrative intervention.
• Low ports (80, 443): Many ISP-provided routers intentionally block UPnP requests for privileged ports below 1024, returning UPnPError 606 "Action not authorized".

Manual forwarding and port translation

When your router does not support UPnP or rejects low-port mapping requests, configure static port forwarding rules in your router’s administration interface:

1. Direct forwarding: Forward port 2222/tcp (and port 28080/tcp on ASUSTOR only) to your Relay server’s LAN IP address.
2. Port translation: Forward external port 80 to internal port 8080, and external port 443 to internal port 8443. This allows visitors to access published URLs without specifying custom port numbers.
3. TURN media port range: If you enable TURN for calls through firewalls, forward the UDP port range 49152–49167 directly to your Relay. UPnP does not support port ranges, so this range must always be forwarded with a manual static rule.

Tip: Always verify external port access from a mobile phone connected to cellular data. Requests originating from inside your local network can be looped back by router NAT hairpinning, giving the false impression that a port is open to the internet when it is not.