When I try to stream thorough it I'm getting a very low speed with a lot of disconnections.
My guess is that there is some incompatibility with the r11 modem that come inside the kit and the ATEM Mini Pro
How can I solve the problem as it's only appear with the ATEM Mini PRO?
All that give sure that problem exist only at SXR R11e-LTE and this ATEM device.
Then you have a possibility to check and compare with OBS or with other LTE device - means perfect bcs this give us some confirmation.
Next. What we should check and do as end-user site before we send a problem to vendor, means MikroTik.
Where you see the loosing frames in video material? That information you see at Youtube platform ? Do some screenshot.
How exactly you see that is errors in material ?
What difference of "upload speed" you have ? Maybe SXTR not have that speed what is needed for video streem ? You can do a speedtest at both LTE devices and try check what speed exist and maybe ATEM try change a codec/bitrange when it upload, maybe you can lock that in options..
R11e-LTE with firmwareMikroTik_CP_2.160.000_v018 we can try stuff:
* You should check if you not have any queue for atem device, bcs you MikroTik can limit via queue transfers. When you not have any queue your ATEM should reach any speed like other network devices behind SXTR.
* What uploud is neccessary and your r11e-lte have that upload speed via long time period ?
* you should install a logs of changing eNB/PCI to see in logs if you are still connected with the same tower and her single antenna, Watch LTE parameters: viewtopic.php?f=7&t=153622&hilit=watchdog#p768105
* Do you have any logs from ATEM device what can give us a hint what it have a problems ?
This is a strange problem and this point and I try help you, if you have problems with ROS then I help free (only lte stuff) with remote access and chat at Telegram (check my signature).