Yesterday, I encountered slow transfer speeds when moving an ISO file from a TrueNAS SMB share to my desktop, which I suspected was due to Tailscale running on my Proxmox VM subnet router. Windows uses an “Interface Metric” to determine which interface to use for requests, with the Tailscale virtual adapter having a lower metric due to its 100Gbps link speed. By increasing the Interface Metric on the Tailscale interface using PowerShell, I was able to prioritize the Ethernet interface for all other cases and achieve higher transfer speeds. Next steps include switching to a Linux distro and upgrading to a 10G NIC for even faster speeds.
https://danthesalmon.com/windows-smb-tailscale/#