I have this DVB-Card
( https://www.linuxtv.org/wiki/index.php/TechniSat_SkyStar_S2 )
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lspci
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05:01.0 Network controller: Techsan Electronics Co Ltd B2C2 FlexCopII DVB chip / Technisat SkyStar2 DVB card (rev 02)
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It is known only to work properly - especially on transponders with high bandwidth - when Hardware PID filtering is enabled:

"Nevertheless it's clear by now that the SkyStar S2 is only usable for DVB S2 reception with WDM (network, NDIS) driver and hardware PID filtering, not with "open whole transponder" switched on and not with the BDA driver, due to the limited bandwidth. That's a hardware limitation, and there is no work-around for it"
( https://www.dvbviewer.tv/forum/topic/36263-technisat-skystar-s2/?do=findComment&comment=262857 )

On Windows, enabling Hardware PID Filters (e.g. with the help of the software DVBiewer) solves all my reception problems. 

On Linux, using the same card, Hardware PID Filtering seems to be enabled:
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systool -v -m b2c2_flexcop_pci
Module = "b2c2_flexcop_pci"

  Attributes:
    coresize            = "16384"
    initsize            = "0"
    initstate           = "live"
    refcnt              = "7"
    srcversion          = "937B732FA3C0FB0B8A59A26"
    taint               = ""
    uevent              = <store method only>

  Parameters:
    debug               = "0"
    enable_pid_filtering= "1"
    irq_chk_intv        = "100"

  Sections:
========

but the reception on Linux is equal to the one on windows with no Hardware PID filters enabled. 

E.G.:
The reception of the free TV Channel "ITV HD" is not possible. Best you can get is some still pictures for a short time and the rest of is a green an black screen.
With Hardware PID filters enabled on windows running, the reception of this channel works with no problems (same PC, same connection to the dish)

If someone guides me, I gladly offer every further information needed I am able to supply.