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Extremely weird network issue
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Extremely weird network issue

seriesnseriesn Member
edited September 2016 in Help

So I have two boxes,
Box Left and Box Right. Same exact network, same location, connected to same switch and router. Only difference? Box L have a bit newer CPU then box R. But for some reason, Box L have slower download then Box R.

Tried switching port, swapping Connection but for some reason, Box L won't download faster then Box R.

Both of them are running exact same setup (well fresh minimal centos 6 64bit), I am sitting here scratching my head for last 2 hour trying to figure out what could have went wrong.
Any help, any idea would help.


  • same IP range?

  • Yeap yeap. Same block. > @RyanD said:

    same IP range?

  • On box L it would be anywhere from 9-27MB/s anytime while box R does a solid 50+.

  • Have you swap the network card?

  • I have a feeling this might be the case. Just came home. Don't feel like going back again. Will check tomorrow.

    @Jack said:
    If they're supermicro I'm pretty sure the mainboards are going to be different models V2 compared to V3?

    Have you made sure the NIC firmware is up to date and/or trying eth1 on the V2 proc? I can't remember specifics but I recall an issue with X9 boards and eth0 could be that?

    Yeap. They are fine.

    @robohost said:
    Have you swap the network card?

  • Did you tweak sysctl on both boxes? tcp_rmem and the like.

  • Try changing the hard disk and verify if the issue is with the board. ;) Had a similar case with one of my Pi and was able to solve it by changing the exact same hard disk.

  • vpsGODvpsGOD Member, Patron Provider

    Paste your trace route on both server.

  • IkoulaIkoula Member, Host Rep
    edited September 2016

    +1 with @sdglhm can't it come from the hard drive ?

    Can you run fdisk smartctl ?

  • am thinking more of lan card / driver problem / duplex mismatch

  • you can also try different OS like Ubuntu for a change / quick test

  • gestiondbigestiondbi Member, Patron Provider

    Have you check ethtool output?

  • Faulty board is the main culprit. Just swapped out and all is well.

    As I mentioned nic and drives were fine.

    Thank you @jack for pointing out the right response and thanks everyone for your kind help :)

    Thanked by 1DeletedUser
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