Pinging router fails 20% of time

I’ve noticed things have been quite buggy on my network lately. The other day while on the Peplink dashboard screen (I have a Peplink 20L) I noticed that i was intermittently losing connection to the router. Just now, I ran pings to two computers as well as the router. The computer pings never failed, while the router ping failed 20% of the time. I know it’s tough to diagnose without being here, but is there someplace I should be looking for a solution to this problem. My network consists of a number of computers and devices connected to a Cisco 16 port gig switch, which then connects to the Peplink 20L, which then connects to both a DSL and cable modem. My firmware was just updated late last week.

Thanks for any help.