EMB-505 Captain reported icing conditions prevented the aircraft speed limitation to land on landing runway. After a missed approach; multiple delaying vectors; and weather improvement the flight was able to land safely.

Narrative

Squall line moving through where planes could not land RWY XX. Multiple directives/changes; i.e. runways shifted 3 times; headings then holding; icing; speeds. (Into squall line with moderate turn). Told 220; 170 then back to 220 then on final course 150. With anti ice on; could not get desired speed. Opened speed brakes; then dropped gear on final to slow. Noticed green stall donut jumped up to a high airspeed. I said; check speed" twice as speed was rapidly decreasing. Airplane could not hold anything during this phase. AP (Autopilot) was turned off to get better control. Got stall warning. Power applied fully and lowered nose with no improvement. Raised gear and had better control. I reported we were going missed. Vectored around again and requested speeds 170 or better for next vector. Cleared the squall area as we began GS intercept. In my career I have never experienced a worse segment of flight than thisNext time in icing will say unable if assigned unreasonably slow speeds. This was a crazy busy segment and it was difficult to stay ahead of the game with the weather system and rapid changes in ATC directives. Many were assigned holding for 50 minutes and they were discussing diversions. (I do know no slower than 150 gear up in icing; but this event has caused me to loose further faith in this airplane.)"