BOVPN to Azure - Fast and Slow

We have an M390 running version 12.92.

We have setup an BOVPN to Azure over a Comcast fiber connection. Everything is working well except the upload speeds are extremely slow vs the download speeds but only across the BOVPN. If I upload a large file to an external location the speeds are fast both ways.

I have the MTU set to 1400 per the Azure requirements.

Support is telling me this is because of inherent SMB issues. But if I am using a single 600meg file to test and it's pulling it down through the BOVPN in 20 seconds but takes 2.5 minutes to send the same file back to the exact same server, this can't be a SMB problem can it?

The same fast vs slow also occurs if I test using hundreds of smaller files. Download is fast and upload is slow.

Any help is appreciated.

Thank you,



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    What is your ISP download & upload speeds?

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    The download is 500Mbs and upload is showing 480Mbs. The upload speeds when not using the BOVPN are very fast.

    Tech support is finding nothing wrong with my configuration and suggesting it's an Azure issue.

    I guess it's possible but I doubt it.


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    james.carsonjames.carson Moderator, WatchGuard Representative

    SMB is very latency sensitive -- it has to effectively ACK everything that is sent, and won't send more data until that happens.
    The easiest way to test this is to use another protocol like FTP, or a testing tool like iperf, which allows you to send in both directions across your tunnel. If those go more quickly, you know it's the protocol.

    -James Carson
    WatchGuard Customer Support

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    OK that's a good idea, thanks. I'll give that a try.

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