Well again the site connection has dropped out every minute, all day. I've checked squid logs and also bandwidthD and there's nothing to suggest excessive traffic on either end. However the dropouts continue. So I established a private VPN so I could look at the two pfsense appliances side-by-side. The server end never reports a drop-out, however the reconnection from the client end (every minute) is noted in the OpenVPN server logs. On the client side is a repetition of the Inactivity timeout (–ping-restart), restarting log entry.
So I tried something. I disabled the client VPN, then disabled the server VPN, waited a minute, re-enabled the server VPN, then re-enabled the client VPN. And now the connection has worked for the past hour without a drop-out.
So it seems to me the problem is not necessarily due to constant drop-outs, but instead that once an issue occurs, the reconnect doesn't work properly and the client side attempts unsuccessfully to reconnect every minute, but without a full reset, the connection might not be made again all day.
Frustrating…. :(