Bartok directly connect with NAS by LAN cable

While playing songs, i disconnect the LAN cable of Bartok from Switch which is also connected with NAS
No sound after few seconds
Then i connect the LAN cable from Bartok to NAS directly by LAN cable
Sound again but stop after few seconds
i find the IP of bartok is changed to DHCP which is set to Static IP before.
i wish to test the sound quality without Switch
but after unplug of LAN cable of bartok, IP is changed. Possible to do it?

Here’s some information on the loop port:

Thanks a lot. i never noted that use

it seems better without the switch