if i can help you with debug, please tell me how.

Sure, please submit a ticket at StellarMate support so we can follow up: stellarmate.com/support.html

Hmm, after upgrading to 2.5.7 i also ran into troubles using Stellarmate app (on a Samsung S6 Tablet).
I am using a dual-IP setup, one is on the local WiFi, the other one is the Stellarmate WifFi network, where the Raspi acts as a hotspot for the private 10.250.250.0//24 subnet.
I was away from the home network, so the 192.168.0.x network could not be reached, but i wasn't able to create a new device config for 10.250.250.1 (SM hotspot) while being in the same subnet with both devices (Phone and Raspi), because the app got stuck in the optical train setup dialogue. At home, the 192.168.0.x network/node was available again in the app, but i could not connect because of the stuck dialogue. Then i deleted all app data and cleared app cache, so i was able to create 10.250.250.1 config in the app again, but it acted awkward on connect. Nothing worked, i had to shut down the Rasapi using ssh.

I am quite confident that there is a bug which will get resolved with the successful addressing of Christian T's bug and issuing a fix.
If there's a workaround, please post here, in the meantime i'm using Stellarmate OS directly via VNC, which works well as soon as you got the hang of the slightly different EKOS dialogues.

What's your equipment profile? can you share a screenshot? I will try to reproduce this behavior.

Added! I have a zwo (asi462MC) , astrometry and telescope simulator for testing.

Thank I just tested with this configuration over Hotspot running on Samsung Tab S5. Now 5 minutes+ of looping with ZWO ASI178MC without any issues. No issues with optical train manager as well. I found one issue reported by another user in case you JUST have a camera specified and nothing else, then this might cause an issue. I will work on this case tomorrow, but if you specify any other devices in the profile it should be fine.

If its any help, I have installed the latest update 2.5.7 (Bundle 179) on two different android devices. But still have huge problems

For me, any of the the camera shooting functions virtually lock out the interface. It is almost impossible to finish shooting. It can be done but it requires multiple jabs at the buttons (many, many times).

Also, very slow when selecting targets. It is almost impossible because it takes up to 30 seconds for a new category to be loaded, even if there are only a few items to display. By that I mean that the screen will remain blank for up to 30 seconds (sometimes just 10 to 15) while data is being loaded and all buttons will be disabled until loading has completed.

There's also a vertical green line to the right of center, about 75% from the left side of the screen.

Ok we identified one issue that was causing this performance issue. We should have a fix released by tomorrow's night.

I have updated the system but the bug is still here.

We actually found and fixed the issue. However, there are a couple of pending iOS issues that we'd like to fix today before publishing a beta update.

Also for android?

Correct.