[server] Can't access gkrelltopd from client

I have a headless home server (Ubuntu 16.04.1) which I monitor from my desktop with gkrellm. Occasionally, I notice that the CPU utilisation on the server spikes for between 10 and 50 seconds, but by the time I've logged in and started htop, utilisation has dropped again to normal, so I have installed gkrelltopd on the server, and gkrelltop on the client.

I start the client with gkrellm -s <server.fq.dn>

I have the line "plugin-enable gkrelltopd" in my server config /etc/gkrellmd.conf

When I enable the gkrelltop plugin in the client, I momentarily see server processes (openvpn, logitech media server) in the krell, but then gkrellm crashes with the following message:

gkrellm segmentation fault:  gkrelltop  (update_monitor)Aborted (core dumped)

I've also noticed that if I disable the plugin on the server, enabling it on the client doesn't cause a crash, but the krell displays local processes on the client (as you would expect). It is therefore something to do with the client/server coection, rather than the plugin on the client.