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[Solved] Dropping transfer speed from NAS with Mojave  




my iMac is running 24/7 and I have a Synology DS1813 in my network. For a long time this has been a stable combination. Since updating to macOS 10.14 I noticed a strange behaviour.  I was late to 10.14.0 and shortly after installing it I upgraded to 10.14.1. So I can't say if the problem was introduced with .0 or .1

After an undetermined time the transfer speed from the NAS to my iMac drops from over 900 Mb/s to 400 and sometimes even in the 2 digits figure. Unmounting the NAS and immediately mount it again solves the problem for a time. But right now I have to unmount at least once a day to get the original speed back.

Anyone else noticing this or knows a solution?

8 Answers

Try using


as the connection address.


If that does not work, then get Bonjour Browser and see what it says your Bonjour name is for your NAS.


And Bonjour is a way for devices on the same local network to discover each other, and see what services are being offered.  The Bonjour name is just part of that.

On other platforms (such as Unix) it is called "Zero Conf"


This post was modified 2 years ago 2 times by datafornothinandbitsforfree

I wrote a little AppleScript to connect to my NAS via smb with Keyboard Maestro if the connection is lost. So far no loss in speed but I will have to monitor it for a few days. I lost the nice bonjour name in Finder and only have the ip-address there. Will have to research how to change that. Here is the script

on run

tell application "Finder"


mount volume "smb://[email protected]<ip-address>/<share>/"

delay 1

end try

end tell

end run

You should be able to take the name you used from the Finder and append .local as in "my-Synology-name.local"

If that does not work, you should be able to use Bonjour Bowser to find out that Bonjour name, and then append .local to that name.

Bonjour browser! Nice find, @datafornothinandbitsforfree. That's going into CSF. 😉 Nice script here, too, @bamboozle. In theory SMB should be faster than AFP, at least that's how it is for me in most cases.

Bonjour browser! Nice find

Unfortunately, it is a 32-bit App, so its life is limited.  I guess I'll have to start looking for a replacement.



Sorry, I totally did not understand what you suggested. Now I get it. Swap the ip in my script with DS1815.local and voila: on the left side in Finder I can see DS1815.local instead of the ip-address. Thanks!

Glad I could help.

The .local is a generic DNS domain name for your local network.  So instead of which DNS will translate to a website out on the Internet, the .local says to check the Bonjour local network names.


Interesting. Are you connecting via SMB or AFP? And if you connect another Mac at the same time, does it, too, see the drop in speeds? Or are those speeds unique to the one Mac you mention?

I've certainly seen NAS transfer speeds vary widely depending upon several factors, one of which is time transferring data. At some point it's possible that a cache gets depleted and... boom... you're out of data until you fetch more.


I connect via afp. The rate just dropped on my iMac again. So I connected with another Mac at the same time. The second Mac was fine, my iMac still had low speed. Unmounting and remounting on my iMac solved the problem again.

What I noticed is the following. I have several volumes mounted from that NAS. So far, I always unmount the NAS and I have a Keyboard Maestro shortcut that immediately remounts all the volumes again. This time, one of the volumes was busy and did not get unmounted. The speed stayed low until I force-unmounted the last volume and reconnected them all. So, the problem seems not with the mount of a single volume but the connection to the NAS itself (if that makes sense).


It does make sense, yeah, and now we’ve isolated it to that Mac. I’d be curious if you had the same issues connecting with SMB. That’s the new default protocol for Macs, and is something I have much more success with in my setups, too.

It could still be something different, but worth isolating that, too. 


I forgot to mention, that the second computer is running 10.13. So this might be another indication that it is related to 10.14.

I use an automator script that I call from Keyboard Maestro. The script uses "query server" afp://ip and if I just swap afp with smb the script doesn't work anymore. Will have to look into that.


Maybe I'm confused with the terminology. SMB and AFP are "transfer"-protocols. Somehow I was under the impression, since AFP is from Apple that AFP would also be responsible for the bonjour name of my NAS. I just read that AFP and bonjour are two very different things.

I disabled AFP on the NAS, so that I would not connect vie AFP by accident. But I also found bonjour settings in another tab on the NAS but this only seems to be connected to Time Machine. Using the Bonjour Browser I cannot find the NAS except under SAMBA. That does sound a bit like smb, But now I'm a bit confused.

On the left side of Finder I saw the bonjour name of my NAS when connected via AFP. Now, connecting via smb I only see the ip-address and an ugly monitor symbol. My goal would be to see the name "DS1815" the instead of the ip (and as a bonus a nice icon :))