I'm encountering latency trouble with my 15" 2011 Macbook Pro (running 10.6.7) when on an 802.11n (5GHz) wireless network hosted by a Time Capsule (version 7.5.2). When I ping the Time Capsule, the ping numbers are all over the place, like so:
64 bytes from 10.0.1.1: icmp_seq=216 ttl=255 time=3.461 ms 64 bytes from 10.0.1.1: icmp_seq=217 ttl=255 time=236.725 ms 64 bytes from 10.0.1.1: icmp_seq=218 ttl=255 time=157.924 ms 64 bytes from 10.0.1.1: icmp_seq=219 ttl=255 time=79.511 ms 64 bytes from 10.0.1.1: icmp_seq=220 ttl=255 time=1.295 ms 64 bytes from 10.0.1.1: icmp_seq=221 ttl=255 time=0.833 ms 64 bytes from 10.0.1.1: icmp_seq=222 ttl=255 time=150.669 ms 226 packets transmitted, 226 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 0.718/115.353/303.004/96.717 ms
The location of my computer doesn't seem to matter. My signal shows up consistently at four bars, and I get the same ping results whether I'm in a different room, different floor, or right in front of the Time Capsule.
A second 15" unibody Macbook Pro (Mid 2009, also running 10.6.7) doesn't have this problem on the same network. All pings to the Time Capsule from this second machine report <4 ms.
If I connect my computer via ethernet to the Capsule, I get a solid <1ms ping, as expected. Only the wireless appears to have wild jumps.
I have tried resetting my network settings (deleting all network configurations from the library), disabling IPv6, changing my "Network Location", resetting the PRAM, resetting SMC, recycling power on the Time Capsule, but none of it seems to have had any effect. I've tried to make sure I have no programs running in the background - Software Update has been turned off and running lsof -i on Terminal only reports SystemUIS as having two open IPv4 connections. There is also no significant network traffic taking place, so it's not a matter of congestion.
Any ideas on something else I can try? I'm sort of at a loss as to why one computer is fine and this one is not.