Possible ZTE 831 modem problem -- downloads keep freezing

[melentiev]

Hi all,

I've been trying to troubleshoot this problem for about 2 weeks now (since I've gotten Fusion installed). In short, all my large file downloads via browsers (Firefox or Chrome) keep freezing mid-way, I have to pause/resume them each time. This happens in 99% of the cases when downloading any relatively large files, 50MB+ in size maybe. I suspect this problem affects some of the streaming sites as well. This problem persists through out all my home devices which use my home connection, both wired and wireless connections.

More in detail -- I've had AT&T (3Mbit) for many years before and never had this problem, all my downloads never froze, never stopped. I started noticing this only when I switched to Fusion and started using their new modem (ZXDSL 831II).

The modem acts as a bridge (default configuration) and sits behind my Linksys WRT600N router which is set up for DHCP configuration.

It doesn't seem to report any errors, BER test doesn't show any errors.

Latency Type Interleave
Line Coding Trellis On
Noise Margin(dB) 6.1
Line Attenuation(dB) 40.0
Output Power(dBm) 12.8
Attainable Line Rate(kb/s) 7596
Line Downstream Rate(kb/s) 6419
Line Upstream Rate(kb/s) 1019
Line Mode ADSL2+
Line Status Showtime

I tried turning Bitswap and/or SRA on and off, but that didn't seem to help. I am honestly at a loss here, having to watch for my downloads when they freeze is getting annoying, I've tried different browsers, cleared cache, etc, my hard drive which is an SSD has plenty of space left too.

Internet connection works fine by itself, doesn't seem to drop, but file downloads do. Everything else works fine too, I can stream full HD movies from HBO without any hiccups. (yay for Game of Thrones new season!)

All I can suspect at this point is the modem.

Anyone experienced any similar problems? Any advice?

Thanks.

(I've originally posted this on DSLreports as well)

[melentiev]

UPDATE: I hooked up my old Speedstream 4100 modem, downloaded several big files (700MB ISOs), none froze, all worked perfectly. I think so far this re-affirms that ZTE modem was at fault.

Is there anything I can do with my ZTE modem (change any settings perhaps that could fix its problem?), or should I ask Sonic for a new modem? (I'd go for another brand even, I've read too many negative reviews about these units).

[virtualmike]

Call 611 on your Fusion line and discuss the issue with the fine folks there. They can confirm settings, and if necessary, do diagnostics on the line.

This page will tell you how long you may have to wait if you call.

[cduran]

Hello melentiev,
I haven't been able to reproduce these symptoms in our lab. Have you had a chance to call in to support yet? I'd be interested in seeing whether a simple factory reset has any effect. If you've already tried that without results, it sounds like shipping you a loaner ZTE 831 may be warranted.

Give us a call at your convenience so that we may troubleshoot further, and potentially arrange for a replacement unit.

Best regards,
Chris

[perrytsao]

Was there any resolution to this issue? I have been having similar issues with "large downloads" (> 5MB). About 50% of the downloads get cutoff.

My equipment was different - it has been occurring with a Motorola 2247 modem, not a ZTE 831. So maybe it's not a modem specific. I haven't had a chance to try a different computer yet, but the laptop that I've been having this problem with works fine when on a different network.

[georgeharter]

The difference between a Speedstream 4100 modem and a ZTE or any other newer modem or gateway is the download speed. The Speedstream is slower, so if it works and the others don't work reliably you have two choices. Either have Sonic support slow down your line a little to increase your SNR Margin or clean up your DSL line to eliminate all possible sources of noise.

If you have some knowledge about phone wiring, the best solution is to use a separate cable for your DSL line going directly from your incoming phone wiring to your modem. For me the problem was a house alarm system, but there are lots of other noise problems. By using a dedicated cable from the point of entry of my phone line to my modem the SNR Margin increased from 6 to 12 and all intermittent sync problems were gone. FYI: the SNR Margin is one of the items on the Status page of your modem/gateway if you know how to get into that from your web browser.

Sonic lets a SNR Margin of 6 pass to keep the download speed up. This might be OK for most computers, but I found that a SNR Margin around 8 provided much more reliable service. I needed a SNR Margin of near 8 for streaming Netflix, kind of like a large download. Lots of problems like this on the Forum.

For people that don’t understand any of this you might need a tech at you house to help with wiring or show you how to check for line noise. Some of the people at Sonic support look for this right away and some seem less knowledgeable. I am only relating my story, but definitely solved my problem.

[melentiev]

Thanks for the responses. I only have ~5Mbit connection due to my distance to the CO, so using either older SpeedStream or ZTE makes no difference in speed. On the other note, I believe I have resolved my original issue - a problem with SPI/firewall blocking DHCP packets for renewal hence connection dropping momentarily every 5 minutes. What is interesting is that this never happened before when I had SpeedStream modem on AT&T connection, neither did it happen with the SS modem on Sonic.net connection - which led me to believe this only occurred with the ZTE modem that I had to customize my firewall to allow for proper DHCP communication.

Similar problem another user described at this thread: viewtopic.php?f=10&t=726 and my detailed response here: viewtopic.php?f=10&t=726#p4334

[georgeharter]

Hard to believe that an ADSL1 modem and an ADSL2+ modem sync at the same speed regardless of line length. But that's really not important. Anyone reading this needs to keep in mind the original message that higher speed DSL lines require less noise to work properly and sync reliably. Sonic.net does not emphasis this enough. I did a self-install from AT&T and was surprised by the fact that there were absolutely no instructions, CD or troubleshooting info included with the modem/gateway and very little on-line. I guess they have changed that now to require all new clients to rent the gateway. Anyway read the original post about line noise and clean up your line, if possible, for better, more reliable service.

[thulsa_doom]

The great majority of speed gains between ADSL1 and ADSL2+ are to be had in the higher frequency tones. ADSL1 and ADSL2 use 222 tones to carry downstream traffic, ADSL2+ uses 478 tones. The higher-frequency tones are more susceptible to attenuation, so at longer loop lengths there's not much difference in downstream capacity between and ADSL1 and ADSL2+ modem. At around 50dB attenuation the difference is pretty small in maximum speeds (~300kbps). At 55dB it's nonexistent.