Occasional latency lag on the 5Gz Network

I get occasional latency spikes when playing league of legends on the 5 Gz Network. The 2.4 Gz Network is more stable. The ping would spike to ~200 every interval.
e.g.
86ms
239ms
90ms
203ms

How can I fix this problem?

Firmware Version:3.0.0.4.318

Thanks,