无静态IP的4G/5G环境下实现Site to Site VPN的硬件设备咨询

Hi Michael, great question—this is such a common pain point for remote sites relying on cellular connectivity! Let me break down some hardware solutions that’ll let you set up a site-to-site VPN without needing a static IP, even with no servers at the new location:

• Leverage your existing WatchGuard devices first (no new hardware needed!)
  Most modern WatchGuard Fireboxes support Dynamic DNS (DDNS) integration. You can configure a DDNS service (either WatchGuard’s native DDNS or a third-party one like No-IP) on your 4G/5G-connected WatchGuard. Then, instead of using a static IP in your Branch Office VPN setup, use the DDNS domain name. The DDNS will automatically update whenever your cellular IP changes, so the VPN tunnel stays connected. This is the most cost-effective fix since you’re using gear you already have.

• SonicWall TZ Series (e.g., TZ270)
  These entry-level firewalls are built for small remote sites and natively support site-to-site VPNs with dynamic IPs. They play nicely with 4G/5G modems (some models even have built-in SIM card slots!) and can use DDNS or SonicWall’s own dynamic VPN mapping to maintain tunnel connectivity. Setup is straightforward, which is perfect if the new site doesn’t have on-site IT support.

• Cisco ISR 1000 Series
  If you’re already in the Cisco ecosystem, these integrated routers support LTE modules for 4G/5G connectivity. They use Cisco’s Dynamic Multipoint VPN (DMVPN) technology, which was designed specifically for dynamic IP environments. DMVPN automatically establishes and maintains VPN tunnels between sites, even when IP addresses shift. It’s a solid choice if you need to scale to multiple remote sites later.

• Ubiquiti EdgeRouter X (with LTE Module)
  A budget-friendly option that’s great for small, low-traffic sites. Pair it with Ubiquiti’s LTE module, and you can set up either IPsec or WireGuard VPNs (WireGuard is lighter and faster for dynamic IP scenarios). The EdgeRouter supports DDNS, and its configuration is flexible enough to handle your use case without needing a server.

• Peplink Balance One
  Built for multi-link reliability (including 4G/5G), this device has native site-to-site VPN support for dynamic IP endpoints. It also offers link load balancing, so if your cellular signal drops temporarily, it can fail over to another connection (if available) without dropping the VPN tunnel. It’s ideal if you need high uptime for your remote site.

A few quick tips to make sure your setup works smoothly:

• Always enable DDNS on your chosen device—this is the core of making dynamic IP VPNs work.
• Turn on VPN keepalive settings to prevent tunnels from dropping due to inactivity.
• If you stick with WatchGuard, double-check your device’s documentation for DDNS setup steps—many users overlook this built-in feature!

Hope these options help you get your site-to-site VPN up and running without hassle. Let me know if you need more details on any of these setups!

备注：内容来源于stack exchange，提问作者Michael