It turned out for few days for unknown reason my SMB share from my DS218+ was not accessible to other Windows machines and I didn't notice and I didn't get any alerts. I saw similar issues in the past and I was not able to find a reason. The only thing that works 100% is clearing SMB cache. Then that share (accessed by ip, e.g. \\192.168.1.181\home from Windows machines) becomes readily available.
I'd like to have that cache clear on autopilot nightly - how would I do that?

I'm having a problem with Apple Time Machine which crops up every few days, where my MacBook Pro says my DS718+ doesn't have the required "capabilities" to perform a backup. The solution for this I've found, is to clear the SMB cache in the control panel, which clears the issues right up.

Therefore, I'm wondering if there's a way to schedule clearing the SMB cache daily, so I don't need to login every couple days. Any ideas?

After upgrading to DSM 7, I was noticing very sluggish performance when browsing files on the NAS via the MacOS finder. My network was excluded as being the problem. Everything is connected by wired 1 Gbps connections. Using iPerf, I tested from the Mac to a Docker instance on the Synology at > 500 Mbps. But, I wasn't getting a tenth of that when browsing files. Directories opened very slowly, and opening a typical 5MB JPEG photo would take about 7 seconds. In the Synology Web interface, things were fast, including in Synology Photos and File Station. I could download a file much faster from the web interface than I could access it via SMB through the MacOS.

This was solved by going to Control Panel->File Services->SMB->Advanced Settings, and in there, selecting Clear SMB Cache. I don't know why, but that made a huge difference and everything is fast now.

Recently, I have notice that directory browsing performance on the SMB server on a DS920+ has been really poor. I don't know if this is due to a recent update or not. I tried clearing the SMB cache. It does fix a few problems but ultimately some of the directories with a lot of files take really long to load.

As an experiment, I ran SSD Cache for over a week and it indicated that I needed 240Gb of Cache for a 10 Tb system. I installed a Samsung Pro 980 500Gb NVME. I don't think the SSD is supported, but I figure if there is a problem, I can just remove it. The system has external backup and power backup.

I then enable the cache for 240 Gb and it told me that this will result in 97K of additional memory. I then tested the SMB and note that directory browsing is now a lot smoother. It might still take a while to load the first time, but then the directory appears to be cache and becomes faster. I don't think it will affect copies and other operation, but it seems to improve directory loading.