Reading that PN thread about ip addresses made me think of the irc days when sometimes if I was allocated certain ip addresses I'd get warnings when connecting to the server.
I remember it would suggest a website address were you could put the ip address in and it would tell me if it was any Internet ban list. It checked about 20+ lists and if it was then some of them you could apply for it to be removed. Some were spam lists. So its possible if the ip address is on the list then thats why cloudflare keeps throwing up this security check.
If you're on a dynamic ip address then turn your connection off and wait for a while, hopefully when you re-connect you'll get a new ip address.
If you're on a static ip address then you'll have to look up the spam check sites, though I've forgot the name of the site the irc server used to recommend. Hmm, you could try this site
https://www.dnsbl.info Btw, its normal to be blocked/banned from a couple of the servers it checks.