The same thing happened to me over a week ago. Im not sure what caused it. Besides Diversion I was also running skynet and stubby. The syslog showed nothing unusual.
Do you run stubby?
I do not use stubby. I had 'internet' because an external monitoring didn't give a down report. My ASUS therefore still responded to ping requests from external sources. Only internally 'DNS' no longer worked. I did not an internal ping.