Looking at the network graph, I keep getting spikes in RTT, PNG and outgoing packet loss (orange and white bars showing). I only seem to be getting these kind of lag spikes in Overwatch.
First double check your router and computer for any configuration issues. This guide will help:
Just a same. Ping Spikes/Packet Loss on EU servers
NetGraph with packet loss 0.9%-1.5%-3%, but WinMTR not showing it.
This is problem of Blizzard servers or routing after as57976.net. My ISP and router works fine.
Some people have the same problem with ping spikes.