From your logs:
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Got notification of changed network (first change: 1)
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Quick dispatch of network change.
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Creating new service.
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Got notification of changed network (first change: 1)
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Quick dispatch of network change.
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Creating new service.
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Got notification of changed network (first change: 1)
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Quick dispatch of network change.
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Creating new service.
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Got notification of changed network (first change: 1)
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - NetworkService: Quick dispatch of network change.
Mar 29, 2024 20:01:18.959 [140433938979640] DEBUG - NetworkInterface: Watching for changes on the interfaces.
Mar 29, 2024 20:01:18.959 [140433934760760] DEBUG - Network change for advertiser.
Mar 29, 2024 20:01:18.959 [140433934760760] DEBUG - NetworkService: Setting up multicast listener on 0.0.0.0:32414
Mar 29, 2024 20:01:18.959 [140434009954960] DEBUG - NetworkService: Creating new service.
Mar 29, 2024 20:01:18.959 [140434009954960] DEBUG - NetworkService: Got notification of changed network (first change: 1)
Mar 29, 2024 20:01:18.959 [140434009954960] DEBUG - NetworkService: Quick dispatch of network change.
Mar 29, 2024 20:01:18.959 [140434009954960] DEBUG - NetworkService: Creating new service.
Mar 29, 2024 20:01:18.959 [140434009954960] DEBUG - NetworkService: Got notification of changed network (first change: 1)
Mar 29, 2024 20:01:18.959 [140434009954960] DEBUG - NetworkService: Quick dispatch of network change.
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - Network interfaces:
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - * 1 lo (127.0.0.1) (00-00-00-00-00-00) (loopback: 1)
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - * 3 eth1 (192.168.0.19) (90-09-D0-20-64-EE) (loopback: 0)
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - * 4 eth0 (192.168.0.18) (90-09-D0-20-64-ED) (loopback: 0)
Mar 29, 2024 20:01:18.958 [140434009954960] DEBUG - * 5 eth2 (192.168.0.20) (C8-7F-54-9A-76-0B) (loopback: 0)
Mar 29, 2024 20:09:16.163 [140433938979640] DEBUG - NetworkInterface: received Netlink message len=1196, type=RTM_NEWLINK, flags=0x0
Mar 29, 2024 20:09:16.163 [140433938979640] DEBUG - NetworkInterface: Netlink information message family=0, type=1, index=3, flags=0x11043, change=0x0
Mar 29, 2024 20:09:16.163 [140433938979640] DEBUG - Network change.
Mar 29, 2024 20:09:16.163 [140433938979640] DEBUG - NetworkInterface: Notified of network changed (force=0)
Mar 29, 2024 20:09:16.163 [140433938979640] DEBUG - Network change notification but nothing changed.
Mar 29, 2024 20:09:17.538 [140434000321336] DEBUG - handleStreamRead code 104: Connection reset by peer
Mar 29, 2024 20:09:17.538 [140433998211896] DEBUG - handleStreamRead code 104: Connection reset by peer
Mar 29, 2024 20:09:17.538 [140434000321336] DEBUG - NotificationStream: Removing because of error
Mar 29, 2024 20:09:17.538 [140433998211896] DEBUG - NotificationStream: Removing because of error
You are using three separate Ethernet connections. Notice how your network is constantly changing, this is caused by the multiple IP Addresses/Interfaces.
You can try setting the IP Address/Interface to use in Plex Settings > Network > Preferred network interface, but that does not always work as expected.
I recommend that you ‘bond’ those connections in DSM Control Panel > Network > Network Interface > Create > Create Bond, so that your NAS/Plex has a single IP address and then try connecting Plex on your TV again.