Did the pihole -d today (Sun 19/Sep) after a successful update I noticed the yellow warning triangle in the upper part of the web gui.
The diagnostic show the rate limit has been applied to my router? Not sure why and I am now worried if I have done a wrong configuration or what the impact could be as the device is my router = access to the world from our whole internal network.
Any advice or suggestions / or help is much appreciated.
I understand I can disable the rate limit, but before I want to fully understand if I have done some kind of wrong setup of pihole.
You have not. The rate limit has been in effect for several versions now, but only in the most recent release (FTL 5.9) do we show a diagnostic message when the rate limit is reached. Previously, clients were rate limited silently.
If all your queries to Pi-hole come from the router IP, this is likely the case. Instead of individual clients being seen (each of which will be evaluated independently for rate limiting), all the traffic is coming via the router on a single IP and rate limiting is applied to this single client seen by Pi-hole (which is actually the combined traffic from all your devices).