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I'm having a problem very similar to the one described here: Downloads pause and time out frequently

The problem appears to be happening with a small amount of customers when they try to download zip files or mp4 files from my website. It doesn't happen with everyone, it happens with about 5% of customers I have I would imagine.

I've changed servers 3 times and the problem persists across all servers.

I'm usually able to replicate the problem myself, I have an LTE 10mpbs connection. I have a suspicion that the problem relates to MTU settings, or ICMP settings, though I have no idea how to tweak either of these on the server. I have a suspicion the problem is only experienced by customers either using a mobile connection, a DSL connection, or a certain type of router.

Since this problem happens on the 3 different servers I've transferred my website to, it must have something to do with the server/website configuration I'm using. I do use a particularly complicated script to host downloads (it embeds the username of the member that is downloading the file within the file) but even outside of the script the problem persists.

I've had multiple system admins try to tweak server settings but nothing has worked, and most are a little skeptical since they themselves are unable to replicate the problem.

Server is running CentOS 6.5, 16 cores/32 threads, 128 MB ram, apache 2.2.29 with cpnginx

*When I only download one file at a time, nothing seems to go wrong, but when I try to download multiple files at once is when I'm able to replicate the issue.

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user241678
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1 Answers1

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This sounds exactly like the MTU issue you allude to in your post. The solution is probably MTU clamping, which can be done with an IPTABLES Command -

Router Version

iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

Server Version

iptables -A OUTPUT -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

davidgo
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