VISITORS blocked again and again what is going on?

I use a site monitoring tool after a year and so without issue m I kept receiving notification that my site was down but when I visited my site
every thing was OK so I thought some thing was wrong with that monitoring service until today I was surfing my site from a friend home all of the sudden the site could not be connected, I come home and check to see when I disable mod security every thing is OK

What is going on ? I was doing absolutely nothing when I surfed the site so this is very big issue I am now worried very much
This mod security thing is costing my money please advise I have disabled this

I also noticed it is happening with all servers with mod security and not just one particular one that has only one meaning
It means some rules have changed within your service

Can you provide auditlog for cases of access blocking from your friend’s home?

No unfortunately I do not have it because I do not know his ip address and I am out now but

in another server that site monitoring tool was blocked the rule id was
217270 CRITICAL 403
So I had to disable the rule id

Now this monitoring tool with their IP has been monitoring my sites for years how it comes this rule is blocking it from time to time?

Can you please explain when this rule id came to existence ?

It comes up 6 Apr 2017 and has been removed during last update 10 Apr 2017.

It gave a hell of a time to a lot of people world wide so much pain . Do you know what it feels to wake up in middle of night being notified that your servers are down ? My wife and me for many servers and when we check every thing is OK we sent back and forth many emails to the monitoring service
and they say every thing is OK

What a stupid nonsense rule .