Network setup advice needed with 2 NICs (one to router and second - direct link to workstation)

[Sergaent]

Hi

I'm wondering if the following setup is possible in Truenas SCALE Bluefin:

Current setup:
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NAS
(1GbE NIC eth0), no IP assigned, DHCP server (piHole), linked to Router/Internet gateway (1GbE) 192.168.1.1
(2.5GbE NIC eth1), not used

eth0 is a part of the bridge br0 (for apps). The bridge has a static IP assigned - 192.168.1.15

Workstation, win10, (2.5 GbE), 192.168.1.3 (dynamic reserved IP) linked to the same Router
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I want to re-link the workstation directly to NAS eth1 to achieve greater speeds to/from NAS and leave NAS eth0 connected to the Router

What should I setup on the NAS side for the workstation to still have internet access re-routed by NAS to Router and (optionally) have the same IP - 192.168.1.3?

Tried to add eth1 as a member to br0 - it works but connectivity constantly drops and restores due to loops/spanning trees as described in this thread https://www.truenas.com/community/threads/best-use-for-2nd-nic.85067/

So - I'm looking for any NAS configuration solution to enable a workstation-NAS link without losing internet access on the workstation.

I have very basic knowledge of networking and any help would be greatly appreciated

Thanks in advance.