TP-Link Router Latency Increase
In January 2025, I started monitoring my network with Smokeping.
I had previously noticed increased latency when a Velop router was connected via powerline ethernet. After upgrading it to OpenWrt, I put that particular Velop back on my network via a $20 TP-Link 8 port 1GbE router. I saw a much smaller increase in latency using the router versus a direct cabled connection.
Smokeping latency of Velop router
The “spike” at the beginning of April is the same “mesa” or plateau visualized in my previous post about the effects of the powerline ethernet. The graphic above is for a much longer time period than the powerline ethernet post, about 5 months, January to June, 2025. The X-axis span of the mesa is much smaller, so the variation in ping latency, previously appearing as black fuzz, looks like much greater latency on this graph.
Detailed smokeping latency
Above, a zoom-in on the X-axis scale. The period above “Week 15” is the time the Velop was cabled via the powerline ethernet. During the period above “Week 16”, there are no data points. I had this Velop and my AX6000 cabled incorrectly, so neither router showed up in the Smokeping data.
The item of interest for this post is the little step up in latency that starts just to the left of the W in “Week 17” and carries on all the way to the right. Before the step, the Velop WiFi access point was directly cabled to my server. After the step, a TL-SG108(UN) version 3.0 TP-Link 8 port 1GbE router gets the direct cable, and the Velop and AX6000 are plugged in to the router.
Before, the TP-Link router, median ping round trip time is 492.8 microseconds. After the TP-Link router, median ping round trip time (RTT) is 715.4 microseconds. Ping RTT is amazingly consistent before and after. The step is 223 microseconds, but it’s on a round trip, so the ping goes out, and the reply comes back, for a total of two trips through the router.
It’s rare to get to see the effect of some individual piece of network gear. Here, I see that a cheap-o router adds about 113 microseconds when a packet goes through it.