This happens to me too - most of the time but not always. I can't identify why dhclient does DHCPDECLINE, the F4 log during installation doesn't have the reason. It is worth noting that my isc-dhcp-server log has warnings like these:
dhcpd[26608]: reuse_lease: lease age N (secs) under 25% threshold, reply with unaltered, existing lease for X.Y.Z.W -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1785768 Title: [bionic] net-installer dhcp client fails with DHCPDECLINE To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/netcfg/+bug/1785768/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs