Tvheadend

I recently setup TVhedend on my RaspberryPi 3 where I run OSMC on.
The tuners of the Octopus NET v2 have been detected automatically searching for services, mapping them to channels worked out as well as finally watching them on the frontend.

But unfortunately the encrypted ones didn't get decrypted by the Octopus so i searched and only found this solution here:
Hendrik Noack wrote:

I was using the OctopusCast tool to create the links and was feeding the encrypted channels to the IPTV module of tvheadend.

You can also create a m3u file from OctopusCast and load it into tvheadend.

https://tvheadend.org/boards/13/topics/11716?r=28661#message-28661

In my case using the generated m3u file didn't worked but as it's just about 7 channels I added them manually to a therefore created IPTV network and took the EPG from the corresponding DVBS2 channels.

But not there is a little but quite annoying "bug" I face now.
Indifference to the "normal way" from channel to channel in the DVBS2 Network it seems subscribes too fast to the new channel of the encrypted ones from the IPTV network.
Such that the server can not provide me a new stream from the same tuner as it is still locked by the old channel. (or something goes wrong when unsubscribing/terminating the previous stream).
Due this it hands the stream request over to the other tuner (just got two and the other one is right now not connected) which can't serve it and tvheadend reports "No input source available for subscription" as well as on the frontend.

So i got finally 3 questions:
1) would there be a other workaround like the one of Hendrik Noack/me
2) where would I have to tweak to get longer channel switching time when switching channel from the DVBS2 to the IPTV network (thats when it usually happens and if I stop by myself stream and fast start the other one it does not occur [no clue if it is due the delay or the manual stopping inside kodi])
3) could there be some other errors source? ( as i for example get also following error codes when starting an "IPTV stream":

TS: astraM3U/ORF 1 HD/ORF 1 HD: H264 @ #1920: Invalid start code 6c:db:9a
TS: astraM3U/ORF 1 HD/ORF 1 HD: AC3 @ #1922: Invalid start code 1a:86:a4
TS: astraM3U/ORF 1 HD/ORF 1 HD: AC3 @ #1921: Invalid start code 84:f9:d4
iptv: invalid error code 501 for 'rtsp://@10.0.0.33/?src=1&freq=11303&pol=h&msys=dvbs2&sr=22000&pids=0,107,1920,1925,1921,1922,1920&x_pmt=107'

i haven't checked strict SAT>IP at the Octopus, if this could be a source?)

Thank you already in advance for each constructive thought