It's just hard. You have to micro both units following a path up the left through the asteroid field to avoid the lancer. Just keep at it, there is a lot of RnG with this one. I usually skip the mission to avoid the headache of having to try a couple dozen times just to beat it. Just know that if you don't play it you will be locked out of the Endor battle. Good luck.

https://www.youtube.com/watch?v=r78GAm5wOzg


This video shows how to beat the mission