TOPIC:

The CURL error appears to be IPV6 related when the host connects to the centos repo, it does try another host and looks like it succeeds.

I don't see an ARP error unless you are referring to the bit about "0 responses" which is OK/expected since we are just sending a gratuitous ARP.

The installation does appear successful. The message at the bottom instructing to create an SR, etc.. will not appear if there is an error with connecting DRBD and starting the sync. Since the message is there, the installation got to the end and DRBD connected.

After some work we got it working. The Active-Active and Active-Passive settings don't always work in CentOS. Turning off one of the bonded NIC and turning it back on should work, using the LACP MAC option should work, or only using one interface (not using a bond) works (this is the option I took for testing and I'll be trying the LACP option later. The CURL error I referenced seems to be that that repo is offline at the moment or its DNS is borked. Thanks again to Sal, he went above and beyond to help.