Starting in fall 2015, I have been getting intermittent periods of high latency wifi connections (pings > 1200 ms) to my 5th Generation AirPort Time Capsule (A1470, 2 TB). High ping periods tend to last 30 min or more, but they do pass. Sometimes they occur every day, sometimes more rarely. All client devices are affected during these periods (MacBook, iPhone, iPad, Apple TV). All client devices are using the latest (general public release) versions of their respective operating systems.
Since this problem started, I have changed home addresses. I've changed modems. I've changed the ethernet cable connecting the TC to the modem. These things didn't help. I have NOT changed ISP, yet.
It's not local interference. That would be plausible in my old apartment downtown, but now I'm in a place where there are very few networks around, and I've used Wireless Diagnostics to establish that there are no channel conflicts. I have no cordless phone, baby monitor, or anything like that.
When I changed modems, I went from a modem-only unit to a modem+router. For awhile, I used the router function from this device (it's an older Cisco, given to me by the ISP). I did not experience the high pings while on that router, but (a) the range was not very good, and (b) I would prefer to have the TC's Time Machine function. Now, the Cisco modem+router is in bridge mode.
Now here's the kicker that has me pulling my hair out: I get the same latency issue when I use my older AirPort Express (A1264). I've verified with two tests. I have done factory resets on both the TC and the APE before re-establishing networks. Before too long: latency.
Given all these variables, I can only see a few possibilities:
1. Something about the firmware (I get the problem whether it's 7.6.4 or I update to 7.7.7).
2. Both the TC and APE have somehow flaked out in exactly the same way.
3. There's a local client that is somehow screwing up the network. I'm doing tests of this now, but it's tedious because of the intermittency of the problem. Everything is tedious because of this. Anyway, I don't even know if this is really possible. And, why did it just start last fall? I got a new iPad Mini, but the problem definitely occurs even if the Mini is powered off. Around the same time I also got a 4th gen Apple TV, but again, the problem has occurred when the ATV is not on the wifi network.
4. I'm trapped in Dimentia Five. Although, closing my eyes doesn't help.
Please advise.
