Ubiquiti UniFi gateways use SLA (Internet Verification) probes to determine WAN health and trigger failover events.

By default, UniFi relies on Google DNS (8.8.8.8) and Cloudflare DNS (1.1.1.1) for these checks.

While convenient, these addresses are not ideal for SLA monitoring, particularly 8.8.8.8, which is known to rate-limit or deprioritise ICMP (ping) traffic. This can result in:

And yet, we’re seeing extreme levels of ICMP traffic to 8.8.8.8 and 1.1.1.1 originating from our network. Why would a DNS server ever be a reliable ICMP probe? Imagine networks all over the world constantly hammering these addresses. We’re fortunate that Ubiquiti is generally considered an advanced platform - many other vendors would likely behave the same way, or worse.

The following UniFi default probes:

Public DNS services are not designed for continuous ICMP probing:

Packet loss to these addresses does not indicate a fault with your connection. If your router marks the WAN unreachable based on the packet loss to these destinations it's incorrect behaviour that may severly affect your experience.

For example, in this thread on the NANOG mailing list a Google engineer responsible for the DNS infrastructure behind 8.8.8.8 and 8.8.4.4 explicitly stated that responding to pings to 8.8.8.8 is not a service they advertise, is not covered by any SLA, and should not be relied upon - it’s simply best-effort and may be dropped or throttled at any time.

Using them for SLA monitoring can cause:

This behaviour can change at any time and is outside your ISP’s control.

Even a good target can appear unreliable if probed too aggressively.

We recommend:

High-frequency probing increases the chance of being rate-limited and can create unnecessary noise.

Reducing probe frequency often improves perceived connection stability, especially if your router uses SLA results to make routing decisions.

UniFi Gateway allows custom Internet Verification settings. Please use this article from UniFi to configure custom SLA monitors.

You can use one of our probes to test ICMP.

Neptune POP probes in Australia (IPv4):

Neptune POP probes in Australia (IPv6):

Overseas Probes that you can use to test international latency.

IPv4 addresses

IPv6 addresses