Packet loss for Rancher Networks even on localhost?

With correct MTU settings, I cannot send any packets to a container that exceed the fragmentation size. I have tested with 1.6 stable and 1.6 testing. The same appears on IPSEC and VXLAN Rancher Environments.

If I spin a container natively on the same host with vanilla Docker, then larger packets fragment normally and are received by the container.

This is a serious issue for us as our application never receives larger packets. Can anyone help?