No, it's the nsmb.conf on the Mac.I'm guessing that's the nsmb.conf on the NAS? I don't see unix extensions or veto files when
man nsmb.confon macOS.
In DSM's Help it says using the Veto Files feature can impact performance. Maybe if you add screenshots of your File Sharing and SMB Advanced settings then we can compare them against ours. I've not noticed these issues and I have a DSM shared folder permanently mounted in Finder: it is used exactly as I used the USB drive that this replaces... create, modify, and hold media files and libraries.
I'm also on the latest DSM 7.1.1 and it's latest SMB Service. So I think the same as you. Using Ventura on main Mac and Big Sur on old MacBook. I have scheduled uploads from Mac to NAS using CCC 6, which auto-mounts other shares using SMB.
Much of the contents came from a previous post from a good while ago on the old Synology user forum. I can't remember the exact details of the research I then went through at the time as it was a good few years ago, but I have now removed those two lines you mention from the file.
There was until VERY recently an Apple support page that gave an nsmb.conf file to use on Mac clients to Synology servers, but it now seems to have mysteriously disappeared, or at least I can't find it any more.
The best settings to use on a Mac accessing a Synology SMB share is a very arcane subject and there are lots of recommendations floating around. I had tried to distil these into a suitable file but like any tweaks I am sure it could always be improved.
One thing I have seen reference to (in Synology Community) is that this cache issue can arise because there are accesses to the share using multiple SMB versions, causing the cache to get "confused". I don't know the truth of this, but maybe it is the cause. At least I know that I am not the only one experiencing the cache issue. I have, as you can see, added the protocol_vers string to my nsmb.conf file (at the prompting of Telos above) so maybe that will resolve the issue.
I will post my new nsmb.conf which (following some research) I have annotated to try and make the purpose of the specific strings clearer.
You will see that I have disabled the multichannel and wired network settings as both of these are irrelevant for me (and I think most people) as I don't have a multichannel connection from my Mac to the network. I believe that this would only be valid for a Mac Pro anyway which could have multiple network ports installed. I am pretty sure that it would not make sense to use a wired and a wireless connection as the two channels giving the asymmetry (and variability) of throughput, and the general flakiness of wireless connections which IMHV are not really suitable for connections to a file server.
I don't want to take us down a rabbit hole, but it further seems to me that multichannel has only very limited utility and unless there is only one client it should not be used - at present I have the two ports on my DS420+ along with the relevant ports on the ethernet switch aggregated, which has benefits for throughput to the network and failover between the ports. However I do not think it is appropriate to use SMB Multichannel on the server because it needs two ports all the way through between the server and the client and is designed for a single client only. My bet is that there will be lots of people who switch it on not knowing of its limited application.
# Revised 2023-05-11
# Disable packet signing to improve performance as no security issue on secure (non-infiltrated) network.
# Note this is off by default from macOS 10.13.4 onwards although this is ambiguous (Apple HT205926)
# Use NTFS streams if supported (Macs use two streams per file - ADS or "multi-fork")
# Soft mount by default (doesn't keep trying to access share so hanging the client)
# Disable directory caching (ensures Finder folder contents display is up to date)
# Turn off change notifications (Finder maintains folder list integrity)
# Disable NetBIOS because not using SMB 1
# Ensure desired SMB level and prevent SMB 1 (Apple HT211927)
# 1 - SMB 1 only
# 2 - SMB 2 only
# 3 - SMB 1 or 2
# 4 - SMB 3 only (my choice)
# 6 - SMB 2 or 3 (recommended)
# 7 - SMB 1 or 2 or 3 (Apple default)
# SMB Multichannel behaviour (Apple HT212277)
# Disable multichannel support because only one wired network connection
# Prefer wired network (multichannel only) (Apple HT212277)