You’ve two interfaces on the same subnet. This can cause problems with Plex unless they are bonded or configured as active/standby.
Disconnect one of the Ethernet cables and reboot the NAS.
Feb 01, 2023 12:41:54.751 [0x7f7f9fd82b38] WARN - [HttpClient/HCl#7] HTTP error requesting GET https://plex.tv/api/photos/profile (6, Couldn't resolve host name) (Could not resolve host: plex.tv)
The NAS cannot communicate with hosts at plex.tv, which is required to claim a server.
Verify the default gateway is set correctly.
Consider using public DNS servers such as 1.1.1.1 (Cloudflare), 8.8.8.8 (Google), or 9.9.9.9 (Quad9) instead of your ISP DNS.
Test that DNS is working: Synology Control Panel → Regional Options → Time.
Configure the NAS to synchronize with a NTP server, select a server, click Update Now.
You should receive a message that the NAS has synchronized with the selected server.
I did have them separate before but after disconnecting one of the cables like you suggested, I am now able to get through the setup process and it looks like I can now view stuff remotely!