@asch75 said in How to increase time to get DHCP lease?:

Next thing: redesign our network topology and reconfigure the cisco switch/es.

Glad you have it sorted out. All you “need” to do is enable portfast on all of the interfaces where you need to pxe boot from. As you found the dumb switch is the quickest check if its spanning tree or not. Plus with it inline you can image before you get your infrastructure updated. So it has an extra benefit.