weirdly irregular throughput problem with two TCs

Do you have wireless off in the MBP??

If not please turn it off.. even if ethernet is top of the list for connection wireless can cause issues.

Can you please change the ethernet cable over to the Gen3 unit from the MBP and see if you get the same effect.

This seems a strange effect so it might take a bit to track down.

Do you have IPv6 set to link-local only? This is under ethernet setup in the computer.

A 2015 MBP should be using a Thunderbolt to ethernet adapter.. is that right?

throughput is *much* lower in each direction, ranging from 30 MB/sec down to about 7 MB/sec; this correlates with much longer times for the transfer to complete. I'm measuring throughput using the "Network" tab on the Activity Monitor app. Disconnecting the 3rd-gen unit has no effect.

Is the throughput bouncing around .. or does it actually suddenly drop below 10MB/s and stay below that number.

Do another test.

This time create a new folder under the main DATA partition. Copy the file to this folder. Then create another folder and do it again..

Permissions issues can have strange effects and I have seen the copy speed extremely slow due to something in El Capo but I haven't tracked it down it.

Next answer won't be for 2hours at least so take your time.

IPv6 is set to "Automatically." Should it be set to "link-local only"?

Yes, It can affect speed over ethernet.

You're instructing me to create a folder at the root level on TC? What do you mean by the "data partition"? What other partition is there?

There is one true partition .. that is data.. (two other hidden partitions just for local TC access)

Many people mistake the Time Machine sparsebundle and create new partitions and folders in there.. I do not want you doing that.. so I was trying to be clear.. Make a new folder under the root partition.

Shouldn't "link-local only" be the setting on the *Time Capsule*, not the MBP?

It can be in both places..

In the TC it will affect how the internet link is handled. So if your ISP is running IPv6 you should keep it..

The ethernet speed is affected by the setting in the TC and auto doesn't always get the right value.

To correctly run TC with the Mac you should have IPv6 set to link-local only.

See the Apple Doco.

AirPort base station not seen or "An unexpected error occurred" appears in AirPort Utility 6.3 - Apple Support

This is ongoing problem.

It might have nothing to do with your speed issue.. but it is still important part of the setup requirements.

It is a simple check box network in Preferences. (sorry I grabbed the wireless one and don't have el capo running on this computer)

No, quite the reverse.. speed is much poorer over AFP than SMB.

The computer should always use SMB to copy files .. but when you do Time Machine backup it will swap back to AFP due to the requirement for using full extended Apple file structure.

It never hurts to force SMB when you are having problems though. My issue is the Mac does not always pick the right auto settings and tell you next to nothing about what it does select.

odysseus wrote:

Thanks for all your help. However, I'm still dumbfounded as to why TC read speeds are so much slower (most of the time).

Have you clean installed el capitan or is it upgrade installed?

Let me suggest if you want to make progress on this and you upgrade installed, you do a clean install of the OS.. it does not have to be on the internal Mac disk.. you can plug in a USB3 disk (SSD for preference) You can buy 250GB USB drive SSD now for very reasonable prices. And use that for your OS.. and do the test again.

I really doubt this is an issue at the TC end.

I do not have a laptop of such recent vintage but I can test it via a thunderbolt hub on my 2011 MBP and see if I can reproduce it.. but as long as the settings are as I have indicated.. it is not something I have seen.

Hi again.

I have now reproduced the issue.

Please look at the last couple of posts in this thread which has the same issue as yours.

3GB Time Capsule MD033 lowers data rate down to 5Mb/s during large files transfers

I did not have a Gen4 TC to test with so I just picked one up second hand.

The Gen5 TC does not have this issue.. stranger and stranger said Alice.

So tell me your results on the Gen5 .. that will confirm my tests.

I cannot solve the issue by forcing to AFP.. I am going to now have a go forcing to SMB1..

Makes it a lot easier for me to help when I can reproduce it.

EDIT.. CIFS did not help (ie SMB1) so I have found no way around the issue.. it is some issue and it is the TC and El Capo (but that probably means it will affect Yosemite and Mavericks as well) .. Mountain Lion does not have the problem.. as usual with Apple.. they are forcing you to upgrade everything.