Virtualized UTM 9 Home Edition - FTP Bandwidth Issues


I've an strange issue with FTP uploads to other servers / downloads from my local FTP server. I have 60Mbit Up but any FTP connection from various ISPs and daytimes are throtteling arround 16Mbit. My UTM 9 is virtualized on Hyper-V with some external and internal NICs. I have a direct internet connection from within the UTM 9 without any upstream router at the WAN port.

My first thought was a bad peering of my ISP but the issue appears also within the same ASN. My next thought was an issue with Hyper-V (Windows 8.1 Enterprise) so I've tested a third party hardware router and indeed the issue was gone. BUT then I've tested a quick and dirty IPfire and OPnsense setup with the same network settings on Hyper-V and the issue did not appear also.

So the reason pointed to the UTM 9. The next step was to test various settings (FTP Helper, IDS, etc.) but the issue remained. Then I've provided my FTP content via HTTPs on the same server and tests from various ISP stated a download speed of 50-55Mbit.

On the other side, if I download content via FTP from other servers I got the full download speed (depending on the available bandwidth of the offsite FTP servers) but in any way far above of the strange ~16Mbit "limit" of my upload speed.


I have no general issue with my Upload/Download speed but definetly with FTP and my upload connection.

Any suggestions to solve this issue are welcome!



Additional information: Iv'e also tested ftp up & downloads through the UTM to another internal zone and got transfer speeds arround 80MB/s which certainly was limited by the target drive.

Additional information
[edited by: Tom Miller at 6:04 PM (GMT -7) on 28 Oct 2020]
  • Hallo Tom and welcome to the UTM Community!

    Do you see anything related in the Intrusion Prevention log?

    Cheers - Bob

    Sophos UTM Community Moderator
    Sophos Certified Architect - UTM
    Sophos Certified Engineer - XG
    Gold Solution Partner since 2005
    MediaSoft, Inc. USA
  • Hi Bob!

    Sorry but the IPS log does not show any entries related to the FTP connection when I upload a file. It also doesn't help if I disable IPS totally.

  • Disabling IPS does not disable Anti-DoS Flooding protection, Tom, and that's what I expected you to see in the Intrusion Prevention log.  What do you get when you paste the following block at the command line?

    cd /home
    wget --no-check-certificate

    How does the FTP upload speed compare?

    If you're using the FTP Proxy, what 'Operation mode' is selected in 'FTP Settings'?  Show us related lines from the FTP Proxy log if applicable.

    If you're using Web Filtering in Standard mode, show us related lines from the Web Filtering log.

    Cheers - Bob

    Sophos UTM Community Moderator
    Sophos Certified Architect - UTM
    Sophos Certified Engineer - XG
    Gold Solution Partner since 2005
    MediaSoft, Inc. USA
  • I'm not using FTP proxy or web filtering in any way.

    He're are the results, peformed directly on the sophos appliance:

    Retrieving configuration...
    Testing from NetCom BW GmbH (-------)...
    Retrieving server list...
    Selecting best server based on ping...
    Hosted by (Heidenheim an der Brenz) [30.45 km]: 9.109 ms
    Testing download speed.................................................
    Download: 273.41 Mbit/s
    Testing upload speed...................................................
    Upload: 56.82 Mbit/s

  • I've found the time to do a clean reinstall by using the current UTM 9 ISO image. The only virtual hardware change I made was to drop the virtual hard disk and create a new one. At the beginning I used the wizard with the minimum services activated to get internet access. And lo and behold, the issue was gone. Then I imported the latest backup from the origin installation and nothing changed - the issue was gone.