I did not see SMB having issues.
My main issues were unstable Wifi and ethernet connections. Tried also an external 10G adapter.
It did not connect most of the time. Even it did, it dropped connection within 1-2 seconds.
Which ISP? Which modem/router do they use? It supplies the DNCP address?
Why did you get as 10 GbE adapter rather than 1GbE? Assuming you are connecting to the ISP router it is likely that it only supports 1 GbE via WiFi. My Comcast modem supports 6E but I still only get ~1400 Mbps, a bit more than wired ethernet's ~930 Mbps.
Can you return the OWC adapter? No experience with their 10GbE adapters but have had problems with some of their products.
WiFi problems are a b#$%#$% to diagnose.
macOS 13.3 Coming Soon With Fix for Network File Sharing
File sharing is normally done with SMB.
[snip]