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I’m connecting from one MacBook Pro (10.6.5) (let’s call it “1”) to another (10.4.11) “2” via WLAN and afp and both are connected to the WLAN via WPA2.

The router is showing me theoretical connection speeds of 104 MBit/s for “1” and 54 MBit/s for “2”. However, when I’m trying to transfer files (doesn’t matter whether I use drag & drop in Finder or cp in the terminal), it takes eternities: 70 seconds for a 2.1 MB file (~ 250 KBit/s if I didn’t make a mistake). The network activity monitor looks like this during the transfer:

network traffic (There’s no other significant network activity going on.)

Clearly, this is off by several orders of magnitude. Does somebody have a clue what could cause this?

Other network traffic works normal on both MacBooks. As far as I know, I have made no special configurations.

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Is this also a problem when downloading something from a remote server? – Nathan Greenstein Jan 8 '11 at 18:10
@Nathan: no. As far as I see this problem is restricted to afp. – Konrad Rudolph Jan 9 '11 at 11:21
up vote 3 down vote accepted

You should try the transfer in FTP only because FTP sets it's own "MTU". If this sends files very quickly, you are looking at a TCP fragmentation issue, i.e., you are sending TCP packets too large for the router to handle on it's own. I imagine you can tweak the Mac network settings to force fragmentation to 1500 or less per packet.

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Radio interference? How many other wifi spots are nearby? How many are using the same channel as you? Does this only happen with AFP or does it happen with other protocols as well (e.g., HTTP, CIFS, etc)? Are you using A/B/G/N?

What's the memory usage look like on both systems? Is one (or both) maxed out? The traffic seems very bursty. This could indicate that one or both sides can't buffer the stream properly (i.e., not enough free memory).

Do you have the same problems when configured to use an Ad Hoc network? If not then the problem is your WAP.

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This happens only for afp (this is what I meant by “Other network traffic works normal on both MacBooks”). The router supports standards n+g+b and operates at 2.4 GHz. Memory usage is not in a range that should make problems. I’ll try the ad-hoc network idea now. – Konrad Rudolph Jan 9 '11 at 11:37

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