High Latency & Packet Loss on WAN Link – Bandwidth Normal (Meraki MX Evidence)

[Shubh3738]

Hello Meraki Community,

We are facing intermittent high latency and packet loss on one of our ISP links, and would appreciate your insights.

Environment
Device: Cisco Meraki MX

WAN setup: Dual WAN

Monitoring via: Meraki Dashboard

Latency/Loss test destination: 8.8.8.8

Location: Corporate Office

Issue Description
Meraki MX shows latency spikes reaching several seconds (1000–4000 ms).

Intermittent packet loss (1–5%) observed during the same time window.

Bandwidth utilization is normal on both WAN interfaces and has been verified with the ISPs.

No recent configuration changes, firmware upgrades, or internal network changes.

Issue impacts user experience (slow applications, intermittent disconnects).

Observations
Latency and packet loss occur even when traffic is low.

Alternate WAN link remains stable.

Firewall CPU and memory usage are normal.

This points away from LAN congestion or bandwidth saturation.

Question to Community
Have you seen similar behavior where Meraki MX reports high latency/loss with normal bandwidth usage?

Are there any advanced MX diagnostics or hidden checks we should perform to further validate this?

Any recommendations to conclusively differentiate ISP-side routing/fiber issues vs MX behavior?

Screenshots from the Meraki Dashboard (uplink traffic, latency, and loss graphs) are attached for reference.

This is a repeating issue

Current version: MX 19.2.4

2 ISP's 

Both Bandwidth- 200 mbps (Total 400)

[Brash]

The information you've provided is enough to point to the ISP as the problem.

To provide evidence, you can collect packet captures on the WAN interface to show the latency, retransmits etc. Just ensure you test to multiple Internet endpoints (which are not aggressive in traffic policing) to prove it's not related to a single destination.

I've done this before to force an ISP to investigate further to which they eventually found the issue on their side.

[PhilipDAth]

I have previously had to investigate an issue where the customer's link was fine, but the ISP itself was experiencing loss to 8.8.8.8

Try adding an extra test target, like 1.1.1.1, and see if it also has the same loss at the same time.

https://documentation.meraki.com/SASE_and_SD-WAN/MX/Design_and_Configure/Configuration_Guides/Firewa...

[cmr]

If you have SDWAN+ or Insight licensing then you can set up app monitors and it also has a WAN health page that shows usage, latency, jitter and more.