What is the l4tbr0 for?
9: l4tbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
link/ether be:32:f0:a9:ec:19 brd ff:ff:ff:ff:ff:ff
inet 192.168.55.1/24 brd 192.168.55.255 scope global l4tbr0
valid_lft forever preferred_lft forever...