В терминале 
 /system/device-mode/update container=yes
# перезагрузка!

/interface bridge add name=bridge-docker
/ip address add address=192.168.254.1/24 interface=bridge-docker
/interface veth add name=veth-mihomo address=192.168.254.2/24 gateway=192.168.254.1
/interface bridge port add bridge=bridge-docker interface=veth-mihomo

/container
add remote-image=wiktorbgu/mihomo-mikrotik:latest \
  interface=veth-mihomo root-dir=usb1/mihomo \
  dns=1.1.1.1,8.8.8.8 start-on-boot=yes logging=yes

/container envs add list=mihomo-env key=SRV1 value="vless://тут_ваш_ключ"
/container set [find] envlist=mihomo-env
/container start [find]