D4Zero VPN Service for remote work

[UT4LW Yuri Pavlov]

Hello, remote work enthusiasts!

I am often asked about remote operation of SDC + Flex-6/8x00 transceiver.

You can try D4Zero VPN Service

The system is successfully used by some users for remote operation with Flex-6/8x00 transceivers + SDC.

According to our users, it significantly outperforms SmartLink. Users successfully operate in SO2R mode using all SDC systems (Skimmers, DIGI-Modem, Contest, RIG Audio).

This is not an advertisement.

[Simon S (S53K)]

As a long-time SDC user, I can confirm that a VPN-based L2/L3 approach (e.g. ZeroTier / D4Zero) provides a much more stable environment for Flex-6/8x00 + SDC, especially in demanding modes such as SO2R, RTTY, and simultaneous operation of Skimmers, DIGI-Modem, Contest and RIG-Audio.

SDC is highly sensitive to timing consistency of UDP streams (panadapter, IQ, audio, CW keying, PTT, skimmer feeds). When a VPN creates a virtual Ethernet segment, FlexRadio, SmartSDR and SDC behave exactly as if they were on the same local LAN. Multicast discovery, UDP streams and SDC’s event-driven model work without NAT, without port forwarding and without relay servers.

In practice this means:

• significantly fewer lost or reordered UDP packets

• more stable PTT and TX/RX switching in 2BSIQ

• fewer audio and panadapter glitches

• more reliable skimmer and decoder operation

A major advantage of this VPN approach is that it works equally well over 5G, LTE, Starlink and other mobile or CGNAT-based networks, where classic port forwarding or SmartLink often fail. ZeroTier establishes encrypted peer-to-peer links even in these environments, giving SDC a stable and predictable network layer.

Compared to SmartLink, latency is lower and — more importantly — deterministic, which is critical for SDC’s synchronized SO2R operation.

73
Simon / S53K / NA3AA / CQ3A