Found similar issue in kernel mailing list: https://lkml.org/lkml/2019/11/30/119
I don't know anything about these "jumbo frames" thought, but problem is similar to my issue.
Bug#947685: linux-image-5.4.0-1-amd64: NETDEV WATCHDOG: enp5s0f1 (r8169): transmit queue 0 timed out
- Bug#947685: linux-image-5.4.0-1-amd64: NETDEV WATCHDOG: enp5... Vincas Dargis
- Bug#947685: linux-image-5.4.0-1-amd64: NETDEV WATCHDOG:... Vincas Dargis
- Bug#947685: linux-image-5.4.0-1-amd64: NETDEV WATCH... Vincas Dargis
