I can also confirm the fix is working.
„Mitigate MTU issues“ on: all files are playing normally
Hi, I have just applied the June update but don’t have the new MTU option under the SMB client service. I thought the fix was merged?
It was. Please post some logs so we can see which version you are on.
Sam
You don’t seem to be using a Vero.
This only applies to Aarch64 platforms.
Since the June update it doesn’t scan my Nas and all the art etc has disappeared. I can play things only by going into files.
Then you should probably create a new, relevantly titled thread for your issue that includes debug enabled logs and we can take a look from there.
I had the same problem… fixed by @sam_nazarko 's post. Some of these updates need to come with Warning Labels 
Indeed – the Synology ones do… 