A client machine being setup for DHCP itself shouldn’t be causing the user to drop off the network and certainly not reauthenticate. A 5 day lease should be fine.
DHCP clients attempt to renew their lease at HALF of the lease duration, so in your case they would attempt to renew the lease in 2.5 days. If the DHCP server is unavailable, or doesn’t respond, the computer continues to use the lease until another half of the remaining time has lapsed– or roughly 75% of the lease duration. At this point it waits until the lease expires and attempts a renewal of the lease, if the renewal isn’t successful, again becasue the server doesn’t respond, then the client drops off the network and starts the DHCP process from the beginning…. DORA.
<b>D</b>iscovery – Basically, finding a DHCP server to service the client, via MAC braodcast from the client to the network.
<b>O</b>ffer – an offer from a server with IP addresses, via MAC broadcast from the server to the client.
<b>R</b>equest – A request by the client for a specific IP that was offered by a specific DHCP server sent to the server from the client.
<b>A</b>cknowledgement – an Acknowledgement that the IP is the clients from the server to the client.
It’s possible there are collisions on the network, or some other factor not allowing some responses to get back to the client from the DHCP Server if the server is available during these time periods. Try looking for events in the clients event log stating it tried to renew a lease and what happened when it did so.