IPhones causing excess latency on Gateway when charging

[arriflex]

When an iPhone is connected to a charger my gateway monitor complains about increased latency (and other network users complain too ::) ) It seems apparent that iPhones are uploading to iCloud servers, tending to saturate the upstream pipe which is about 10Mbps on my cable connection when placed on a charger. However, when saturating the outbound traffic with an alternative cloud backup service such as Dropbox or Backblaze pfSense is able to avoid similar gateway latency.

In order to throttle the iPhones specifically, I put those device IP's into a firewall aliases and applied a limiter using LAN rules so they wouldn't push more than 5Mbps out through the gateway. This appears to be operational based both on pfSense's traffic graph when someone plugs an iPhone into a charger as well as testing from an iPhone using the speedtest.net app.

However, even with the bandwidth for those devices throttled and verified as utilizing only half the upstream bandwidth the gateway monitor pinging 8.8.8.8 increases in latency until sometimes declaring the gateway as down.

I'm not seeing particularly increased CPU, memory, state or Mbuf cluster during the period showing increased latency. What else should I be looking for to troubleshoot and hopefully prevent the issue?

arri

2.3.2-RELEASE (i386)
built on Tue Jul 19 13:09:39 CDT 2016
FreeBSD 10.3-RELEASE-p5

Netgate 2D13
CPU: 500 MHz AMD Geode LX800 CPU
DRAM: 256MB DDR DRAM