Stream buffering and ftp upload transfer problems with activated firewall

  • Hi,

    I`m running PFSENSE (2.3.2-RELEASE (amd64) built on Tue Jul 19 12:44:43 CDT 2016 FreeBSD 10.3-RELEASE-p5) in a virtual machine (2CPUs, 1 GB Ram) within my ESXi 6.5 Host.

    Internet <–> Modem (FritzBox) <- P1 -- WAN -> HW-Router (Asus) <- P4 (Trunk) -- LAN1 -> ESXi Host <- PFSENSE (VLANs, Routing)

    One of the VLANs is configured with an Gateway that is used as default Gateway for internet access. Do currently have only one cable connection to my ESXi/PFSENSE.
    See screenshots below.

    Since I am using PFSENSE I have problems with live streams e.g. Shoutcast (Online Radio) and uploading files via ftp:21 to my webspace provider.

    LiveStream: The live stream interrupts after ~60-120 seconds.

    FTP-Upload: The first 80-100 files will be uploaded without any problems and then it will begin with connection interruptions.

    What I already tried:
    System\Advanced\Firewall&NAT: Changed Firewall Optimization Options from "normal" to "conservative".

    Result Streams: The live stream is running longer now. The interruptions will start after 10-20min.
    Result FTP-Uploads: Same like before.

    System\Advanced\Networking: I disabled the option "Hardware Checksum Offloading" –> Result: Same like before.

    I also already tried disabling Outbound NAT. With no change...

    I have checked that there is enough CPU and RAM resources.

    System\Advanced\Firewall&NAT: If I enable the option "Disable all packet filtering" everything is working without any problems...
    But I don't like to completely disable the firewall.

    Any ideas what could be the problem here?