{"id":319,"date":"2026-08-29T23:46:04","date_gmt":"2026-08-29T23:46:04","guid":{"rendered":"https:\/\/netguide.io\/network\/unifi-5g-lte-wan2-failover-en\/"},"modified":"2026-08-29T23:47:06","modified_gmt":"2026-08-29T23:47:06","slug":"unifi-5g-lte-wan2-failover-en","status":"publish","type":"post","link":"https:\/\/netguide.io\/network\/en\/unifi-5g-lte-wan2-failover-en\/","title":{"rendered":"Outage Protection: 5G\/LTE as a WAN2 Failover in Your UniFi Network"},"content":{"rendered":"<div id=\"netgu-3278184310\" class=\"netgu-before-content netgu-entity-placement\"><script async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-6258556257245998\" crossorigin=\"anonymous\"><\/script><ins class=\"adsbygoogle\" style=\"display:block;\" data-ad-client=\"ca-pub-6258556257245998\" \ndata-ad-slot=\"3494115342\" \ndata-ad-format=\"auto\"><\/ins>\n<script> \n(adsbygoogle = window.adsbygoogle || []).push({}); \n<\/script>\n<\/div>\n<p class=\"wp-block-paragraph\"><strong>An internet outage today takes down far more than movie night: your home-office VPN, card payments in the shop, or the practice management software all grind to a halt. With a second WAN connection over 5G\/LTE, your UniFi gateway switches to mobile automatically when the primary line fails. This guide covers the principle, the hardware, the setup, and the data-cap trap.<\/strong><\/p>\n\n\n\n<figure style=\"text-align:center;margin:1.5em 0\"><svg viewBox=\"0 0 820 300\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" role=\"img\" style=\"max-width:100%;height:auto;font-family:system-ui,Arial,sans-serif\"><rect x=\"0\" y=\"0\" width=\"820\" height=\"300\" fill=\"#f7f9fc\"\/><rect x=\"30\" y=\"55\" width=\"190\" height=\"44\" rx=\"8\" fill=\"#dcfce7\" stroke=\"#16a34a\" stroke-width=\"2\"\/><text x=\"125\" y=\"82\" font-size=\"13\" text-anchor=\"middle\">DSL \/ fiber<\/text><rect x=\"30\" y=\"150\" width=\"190\" height=\"44\" rx=\"8\" fill=\"#fee2e2\" stroke=\"#dc2626\" stroke-width=\"2\"\/><text x=\"125\" y=\"177\" font-size=\"13\" text-anchor=\"middle\">5G\/LTE router (bridge)<\/text><rect x=\"330\" y=\"100\" width=\"170\" height=\"44\" rx=\"8\" fill=\"#dbeafe\" stroke=\"#2563eb\" stroke-width=\"2\"\/><text x=\"415\" y=\"127\" font-size=\"13\" text-anchor=\"middle\">UniFi gateway<\/text><rect x=\"620\" y=\"100\" width=\"160\" height=\"44\" rx=\"8\" fill=\"#eef2f7\" stroke=\"#94a3b8\" stroke-width=\"2\"\/><text x=\"700\" y=\"127\" font-size=\"13\" text-anchor=\"middle\">Internet<\/text><line x1=\"220\" y1=\"77\" x2=\"322\" y2=\"77\" stroke=\"#5b6b7e\" stroke-width=\"2\"\/><polygon points=\"322,72 330,77 322,82\" fill=\"#5b6b7e\"\/><line x1=\"220\" y1=\"172\" x2=\"322\" y2=\"172\" stroke=\"#5b6b7e\" stroke-width=\"2\"\/><polygon points=\"322,167 330,172 322,177\" fill=\"#5b6b7e\"\/><line x1=\"500\" y1=\"122\" x2=\"612\" y2=\"122\" stroke=\"#5b6b7e\" stroke-width=\"2\"\/><polygon points=\"612,117 620,122 612,127\" fill=\"#5b6b7e\"\/><text x=\"275\" y=\"70\" font-size=\"11\" text-anchor=\"middle\" fill=\"#16a34a\">WAN1<\/text><text x=\"275\" y=\"165\" font-size=\"11\" text-anchor=\"middle\" fill=\"#dc2626\">WAN2<\/text><text x=\"410\" y=\"215\" font-size=\"13\" text-anchor=\"middle\" fill=\"#64748b\">Failover: if WAN1 drops, WAN2 takes over automatically.<\/text><\/svg><figcaption style=\"font-size:13px;color:#64748b\">Dual-WAN: primary fixed line, secondary mobile as a backup.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">The Principle: Dual-WAN With Automatic Failover<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">With dual-WAN the gateway uses two separate internet connections. WAN1 is the primary line, typically DSL or fiber. WAN2 is the backup, here a 5G\/LTE link. In failover mode WAN2 stays on standby and only becomes active once the gateway detects the primary line as down. To do that it constantly sends health probes into the network; if enough of them fail, it reroutes all traffic to mobile within seconds and later switches back automatically.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The alternative is load balancing: both lines run in parallel and traffic is split by weight. For pure outage protection, failover mode is the better choice, because your costly mobile data is only consumed when it truly matters.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The big advantage of a mobile backup over a second fixed line is that it runs on entirely separate infrastructure. An excavator cutting your fiber cable, or a failed local exchange, does not take the 5G link down with it. That independence is exactly what makes the protection robust. Modern 5G networks also deliver enough bandwidth and low latency to carry video calls, cloud services, and VPN smoothly in emergency mode.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Hardware Options<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Option A: A 5G\/LTE Router in Bridge Mode (Universal)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The most flexible route: any UniFi gateway with a free second WAN port plus a separate 5G\/LTE router holding your SIM. The key is running that router in bridge or passthrough mode. It then hands the public mobile address straight to the UniFi gateway instead of building a second NAT of its own. Simply cable the LTE router via Ethernet into the WAN2 port. The upside: you are completely free to choose carrier, plan, and SIM. Mind the reception at the install location, and if the signal is weak, pick a model with external antenna connectors so enough bandwidth arrives when it counts.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Option B: Ubiquiti&#8217;s Own Mobile Solutions<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Ubiquiti offers dedicated devices for this, such as the UniFi LTE Backup for seamless failover of UniFi gateways, plus newer 5G models. In the US market these products sometimes ship with a built-in AT&amp;T SIM and their own data plan. Before buying, always check availability, frequency bands, and SIM freedom for your country. If any of that is unclear, an unlocked 5G\/LTE router in bridge mode (Option A) is the safer bet.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Setup: Assign WAN2 and Choose Failover<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">In the UniFi Network Application you define both connections under Settings &gt; Internet. WAN1 and WAN2 each map to a physical, WAN-capable port on the gateway.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Open <strong>Settings &gt; Internet<\/strong> and confirm the primary line runs as WAN1.<\/li>\n<li>Click <strong>Add Secondary<\/strong> and assign it the port your 5G\/LTE router is connected to.<\/li>\n<li>Choose <strong>Failover Only<\/strong> as the operating mode so WAN2 activates only during an outage.<\/li>\n<li>Set the priority: WAN1 high, WAN2 lower, so the primary line resumes automatically once it returns.<\/li>\n<li>Save and test by briefly unplugging WAN1 and watching the switchover.<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Failover Criteria (Health Checks)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The gateway marks a WAN as down when two of three health probes fail; this Auto SLA is sufficient for most networks. In addition, UniFi watches the primary line for high latency and packet loss and switches over when those persist, not only on a complete outage. The probe target addresses can be adjusted if your provider blocks certain servers.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The Data-Cap Trap<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Mobile plans often come with a limited or expensive data allowance. If your network runs on 5G\/LTE for hours, cloud backups, Windows updates, or streaming can burn through several gigabytes fast. Here is how to limit the damage:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Allow only essential devices onto the failover and lock out secondary ones (TV, guest Wi-Fi) via VLAN or firewall rule during an outage.<\/li>\n<li>Restrict automatic updates, cloud sync, and backups to the primary line, or pause them on a schedule.<\/li>\n<li>Set a data-usage alert with your carrier and pick a plan with enough headroom.<\/li>\n<li>After switching back, review how much data the outage cost.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Typical Use Cases<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">In the <strong>home office<\/strong> the failover keeps VPN, video calls, and cloud tools running. In a <strong>medical practice<\/strong> or law firm, scheduling software and electronic transfers stay reachable. In <strong>retail<\/strong>, card payments keep working when the fixed line drops, instead of costing you sales. Anywhere a few minutes offline costs real money or trust, the second connection pays for itself quickly.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Frequently Asked Questions<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Do I need a specific UniFi gateway?<\/strong> You need a gateway with a second, WAN-capable port. Many UniFi gateways offer this or let you repurpose a LAN port as WAN2; check your model&#8217;s specification.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Why bridge mode instead of a normal router?<\/strong> Two stacked NAT layers (double NAT) break port forwarding and VPN. In bridge mode the LTE router passes the connection cleanly to the UniFi gateway.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>How fast is the switchover?<\/strong> Usually within a few seconds of the health probes failing. Existing connections may briefly drop and re-establish.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Does the gateway switch back automatically?<\/strong> Yes. Once WAN1 is stable again, the higher-priority primary line takes over, so no mobile data keeps running unnecessarily.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Sources<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Ubiquiti Help Center: <a href=\"https:\/\/help.ui.com\/hc\/en-us\/articles\/360052548713-WAN-Failover-Load-Balancing-and-Port-Remapping-on-UniFi-Gateways\">WAN Failover, Load Balancing and Port Remapping on UniFi Gateways<\/a><\/li>\n<li>Ubiquiti: <a href=\"https:\/\/www.ui.com\/integrations\/mobile-routing\">UniFi Mobile Routing<\/a><\/li>\n<\/ul>\n<div id=\"netgu-1549102645\" class=\"netgu-after-content netgu-entity-placement\"><script async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-6258556257245998\" crossorigin=\"anonymous\"><\/script><ins class=\"adsbygoogle\" style=\"display:block;\" data-ad-client=\"ca-pub-6258556257245998\" \ndata-ad-slot=\"4559785002\" \ndata-ad-format=\"auto\"><\/ins>\n<script> \n(adsbygoogle = window.adsbygoogle || []).push({}); \n<\/script>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Set up a 5G\/LTE backup line as a second WAN on your UniFi gateway and stay online automatically when your DSL or fiber fails.<\/p>\n","protected":false},"author":1,"featured_media":237,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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up a 5G\/LTE backup line as a second WAN on your UniFi gateway and stay online automatically when your DSL or fiber fails.","brizy_media":[],"_links":{"self":[{"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/posts\/319","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/comments?post=319"}],"version-history":[{"count":2,"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/posts\/319\/revisions"}],"predecessor-version":[{"id":331,"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/posts\/319\/revisions\/331"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/media\/237"}],"wp:attachment":[{"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/media?parent=319"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/categories?post=319"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/netguide.io\/network\/wp-json\/wp\/v2\/tags?post=319"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}