Reject Private IP DHCP Offer

Can I reject private IP DHCP offers on the firewall?

I’m try to re-ignite this post as I still don’t have a good solution

Can you explain a bit more?

You can reject/block quite a bit on firewall but as previous poster correctly mentions, you may want to explain a bit more what the intention is, why, which context, …

My ISP modem provides an IP in the range 192.168.100.0/24 first then once this is rejected it then provides a public IP

Based on my feeling: nope.
I would think of either doing some scripting (IP change?) or getting a different ISP.
What ISP do you have? And how do you currently “reject” the private IP address offer?

none Mikrotik’s equipment rejects RFC1918 by default, I know this isn’t a bad thing from a Mikrotik perspective but it would be helpful if there was a way to do it.

the ISP is Virgin Media UK

The below article describes the process quiet well

https://theserpent.co.uk/posts/virgin-media-and-modem-only-mode/