Intermittent Internet from LAN, down for several hours but Brume as Tailscale subnet stays connected

Struggling with an issue and looking for any recommendations.

I have Tailscale setup at two locations. Each location has a number of devices that cannot install Tailscale so I have a Brume at each site as a Subnet Router. There are also Windows devices that have the Tailscale client installed.

Site one is my home and connected with FTTP.

Site two is at a farm and is connected with 5G

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