Not getting any DHCP responses for my VMs

I'm not getting any DHCP responses for any VM, neither on ipv4 or ipv6.

So I've tried and tried and I'm about to go bald from pulling my hair on this and neither I nor another much more experienced networking guy can find any other explanation than that something is broken in the network setup outside of my control is broken.

So, the thing is, I've tried now multiple times creating different VMs, different VCNs and so on, in order to try to get it to work. I noticed it when I was trying to get ipv6 working and didn't get a response to that. But, now that I tried adding a second vmnic and give that an IP, that too results in no IP being assigned.