Problem restoring LAN Connectivity on idle PCs

[LNXM]

I just installed OPNSense on one of those Topton-type little boxes with 4x i-226v NIC (igc interface code)

I noticed that after going out of sleep mode, or after sitting idle for a while, PCs on my LAN lose connection to my NAS, and the connections are not readily restored. On one PC, I cannot even remount the LAN share, even though all addresses and interfaces are up and reply to PINGs.

The connections are eventually restored after about a minute, and everything works fine after that.

I did not have these problems with my previous router, and all my other hardware and NAS server is working.

Could this be an OPNSense setting issue, or a tweak I need to do, or are these boxes just not the right ones for OPNSense? 

I'm running:

OPNsense 24.1.6-amd64
FreeBSD 13.2-RELEASE-p11
OpenSSL 3.0.13