Random unexplained slowdowns

We recently started getting really bad slowdowns of broadband WLAN and I'm stumped. It will be super fast one minute and then just clog up the next without any seeming reason. Give it some time and it clears up again on it's own. I can verify the speeds using the Ookla test - see screenshots.

On top of this I had a router go bad so replaced it with a Linksys AC1750/EA6500 - 2 bands - 2.4 and 5GHz.. The router has a nice browser UI that shows all connected devices without having to look up MAC IDs - nothing out of the ordinary. iMac Desktop, 2 iPads, 2 iPhones 6+, 2 Tivos, 2 Apple TVs, PC Laptop, WiFi Printer - all secured - no one hijacking bandwidth. It's 100% strength at all locations over WLAN.

I also replaced the CAT5E cable from the modem to the router as well, but no help. The modem is a Motorola Surfboard Extreme SB6120. Below are some screen shots - one while behaving good and one while behaving bad. I note the cable levels at the modem don't seem to change much when it's good or bad, which makes me think MAYBE the ISP is not to blame - but I'm not sure how to tell. Normally I would think the problem is the ISP right away - it usually is as we have many outages and spotty service from them on cable as well. I'm at a loss as to see if there's anything else eating up bandwidth. I've tried different browsers - no difference. Quit everything on the iMac except a browser - no difference. Tried shutting off everything related to iCloud on all devices - may have some affect but not for certain. We aren't using any other auto-uploading cloud based services of any kind.

Any other ideas? As best as I can determine the slowdown it at the throughput of the router itself but if it's bandwidth - how do I trace the source?

Short of calling the cable company - (who will blame it on my equipment because I don't rent from them) - The next test would be to replace the modem... but I hate to do that if its not at fault. No way to tell AFAIK.

GOOD -



BAD -

iGirl said:

Short of calling the cable company - (who will blame it on my equipment because I don't rent from them) - The next test would be to replace the modem... but I hate to do that if its not at fault. No way to tell AFAIK.

Click to expand...

Probably should contact the CableCo... the modem numbers don't look too bad as all... but you might have some upstream issues on their end...

You should test your internal speed and external speed separately. iperf is good for internal testing.


Your "bad" speed test does seem strange. It looks as though your upload speed was being throttled.

What time of day does the speed test return poor results?

My ISP did not have enough bandwidth, and for about 8+ months my download speed would go from a speady 420 kbyte/sec to a highly fluctuating 10-70 kbyte/sec from about 5pm to midnight, every day.

Nullity said:

You should test your internal speed and external speed separately. iperf is good for internal testing.


Your "bad" speed test does seem strange. It looks as though your upload speed was being throttled.

What time of day does the speed test return poor results?

My ISP did not have enough bandwidth, and for about 8+ months my download speed would go from a speady 420 kbyte/sec to a highly fluctuating 10-70 kbyte/sec from about 5pm to midnight, every day.

Click to expand...

Yep, and when contacting Customer Care - the "logs" page is very useful, along with the "signal" page... I would say that the Log page is actually more relevant with Care...

sfx

Thanks for the replies! There is no day/time pattern to the slow downs - this is something entirely new that's started in the last 2 weeks - we've been running OK for well over a year on the existing setup (with previous router in place)... except for the above mentioned outages etc.

There is an OS X GUI for iperf called jperf but seems a bit complicated - meanwhile OS X does have other tools offering extensive details -
SystemProfile/Network/WiFi
Network Utility (shows 450 Mbit/s)
Airport Contextual Menu

Via these, everything looks OK - though I'm going to take screenshots and compare good and bad on these as well. Looks like it's probably going to come down to getting the cable company out here again...

Your upstream power levels are right on the edge......IMHO once they get around 50 dBmV things can get flakey (lower is better). I'd call the cable co.