Update from last night:
I still cannot force my setup to guide at all.
I decided to postpone fighting with it, and just do some exposures unguided, only tracked.
Got two hours of the Witch Head Nebula, and it barely registered above the noise, did not expect it is that dark.
My new lens is quite sharp wide open, but still I think I will step it down a bit.
Will continue research why I cannot guide.