I must say I am stuck on this mission. I tried both ways, alone or full assault.
Both times I get overwhelmed. Full assault is even a better option for me as it lets me resupply in InCo system before going through the portal. I got 80% resistance to laser on all 6 fighters, got 2 of them with 10hp/s remote repair and my mothership got a 50% resistance to lasers and mostly plasma turrets.
Still my units die, and all allies die before even getting half way to the other portal to summon help from Triada
Going alone was even worse, I could only free that same portal in time and still after that get easily overwhelmed.