Channel blank when sat transponder changed

[daveunit]

! Before you log an issue, have you updated to the most recent version? It's possible the issue may have already been fixed.

Describe the bug / Actual behaviour:
When zapping to a channel on a different transponder, the channel is blank. It works when zapping to next channel on same transponder, also goes when changing back to first channel on the new transponder.

Expected behaviour:
Channel should run normally when zapping to a channel on another transponder.

Has this issue started to happen just recently?
No, the issue has been a problem in all 7.3 and 7.4 versions of OpenATV tested between December 2023 and May 2024.

To reproduce:
Steps to reproduce the behavior:

1. Connect two LANs by using OpenVPN on Asus AC87u at client end and Asus AX11000 at server end.
2. Establish Kathrein EXIP 418 working on server LAN with Ocatagon SX88 v2.
3. Move Octagon SX88 v2 receiver to client LAN, allowing the routers to connect it to the server LAN by OpenVPN.
4. Go to channel 1 on transponder X. Probably blank.
5. Switch to channel 2 on transponder Y. Screen is blank.
6. Switch to channel 3 on transponder Y. Channel works.
7. Switch back to channel 2 on channel Y. Channel works.
8. Switch back to channel 1 on transponder X. Channel is blank.
9. Workaround: turn Octagon receiver off for half a second, then back on. Channel 1 on transponder X works but issue remains when transponder changed.

A Sat IP TV Pro app on a smartphone does not have this issue, but OpenATV does.
Suggestion: It may just be necessary to start the channel feed after a few hundred milliseconds, or retune the PID a second time when the transponder has been changed or if OpenATV notices that it is not playing anything, or more thoroughly initialise the transponder.

Screenshots
Blank black screen. EPG works.

Image/Box Model (please complete the following information):

• Version: OpenATV 7.3, 7.4
• BoxModel: Octagon SX88 v2
• Kathrein EXIP 418 Sat IP

Additional context
Only occurs when connecting to Kathrein EXIP 418 via OpenVPN managed by Asus routers on LANs at each end. Direct connection on same LAN works fine.