I bumped the L2 MTU to 2028, max of that particular unit and set the other side to match, then DNS stopped working. Traffic worked, I could ping by IP but not by name. Of course my DNS server was on the other side of that cable, so a handful of folks were having issues.
I dropped the L2 MTU back to default on MT of 1600, improved, but not 100%. I had the DNS max packet size set to 4048 or so, dropped it back down to 1536, started improving. UDP speed tests were all over the map, then would randomly quit. TCP was decently reliable, though not as fast as they should be. ----- Original Message ----- From: Mike Hammett To: af@afmug.com Sent: Thursday, March 05, 2015 6:42 PM Subject: Re: [AFMUG] downloads stalling but streaming, speedtests, etc. OK Packet capture? ----- Mike Hammett Intelligent Computing Solutions http://www.ics-il.com ------------------------------------------------------------------------------ From: "CBB - Jay Fuller" <par...@cyberbroadband.net> To: af@afmug.com Sent: Thursday, March 5, 2015 5:57:03 PM Subject: Re: [AFMUG] downloads stalling but streaming, speedtests, etc. OK wow....how did you figure that out? ----- Original Message ----- From: Glen Waldrop To: af@afmug.com Sent: Wednesday, March 04, 2015 11:18 PM Subject: Re: [AFMUG] downloads stalling but streaming, speedtests, etc. OK I've got one similar to that. DNS doesn't work. TCP works okay, but DNS just absolutely fails. Turns out the Ethernet port is dying on me. I've got extra hardware in the air, so quick fix is a wireless shot from the AP to the ground to the switch that feeds the PTP shots. It'll work until I can fix it properly. What is happening in my case is the Ethernet is dropping packets, frames, something. TCP retransmits, UDP just disappears. Not sure if that will explain your broken download issue, but it is one of those odd problems. Could be the server side is just dropping the connection after 100+ retransmits. ----- Original Message ----- From: "Ken Hohhof" <af...@kwisp.com> To: <af@afmug.com> Sent: Wednesday, March 04, 2015 10:10 PM Subject: [AFMUG] downloads stalling but streaming, speedtests, etc. OK > > I can't figure this out, but it seems like the sort of thing someone else > here will say "oh, I know what causes that". > > I've been tracking a smattering of customer complaints about downloads > just stopping, and finally was able to reproduce it. I Googled for large > file downloads and took the first one that came up: > https://www.futurehosting.com/network-test-files/ > and found the downloads would stop repeatedly at the same point. > Different for each file and server location, but the same for repeated > downloads of the same file. For example the 100MB file from Michigan kept > stopping at 8MB. It chugged along fine, then slowed dramatically and > stopped, with no traffic either direction. Yet a ping to the same IP > address never had a problem. > > Note it is NOT the computer, the server, or last mile radios. I was able > to see it going only through backhaul radios and routers, no AP/CPE. And > it works fine with the same computer here at my house on AT&T. > > Tomorrow I need to chase it back toward my network border. I am not > conversant with Wireshark so have not done that yet, am not looking > forward to it. One pesky customer claims to have done that and seen TCP > retries and out-of-order packets, maybe he's right, maybe he is just > misinterpreting the data. > > So .............. what can cause HTTP downloads to stall and stop, while > other stuff like Youtube and Hulu and speedtest.net are fine? > >
