As when i put my attention to build up industries to make more robots at the same time, the enemy waves were running over my defenses and crippled my conveyors and ultimately the core, and when i was building up my defenses to stop them, the time wasted there in not building up the industries was allowing more enemy waves to spawn with increased number and firepower outclassing totally by then my robots numbers
Felt like an impossible situation to poor old me
Until i just googled around and saw some people suggestions, i then learned something i didn't knew and that changed the whole battle : when you build an alpha pad to be able to morph your "flying and shooting light drone" into a "walking and shooting light robot" , by pressing left shift (well i changed the shortcut after that to my liking) your walking robot can ... fly (but unlike the flying drone it will then be unable to shoot).
What this changed is that then my walking flyer would just then fly over the impassable borders of the map (escaping enemy fire), then come back from the rear of the enemy base, land and destroy every single anti air turrets in the enemy base that were preventing any air assault leading to the enemy core.
At some point i couldn't get near enough of the enemy core to shoot as it was still protected by many artillery turrets that would easily and fast destroy my walker (and the walker robot when flying can't shoot) and were outranging it by a lot.
once respawning in my camp i just went back to the alpha pad to morph my walker robot back into the flying drone, then fly again over the impassable stuff and easily get from the rear of the enemy base to attack its core (as there's no more legion of anti air turrets) and destroy the enemy core from a safe distance as artillery is nothing to flying things.