PCE-AC68 not picking up 5GHz channels

Hi, I live in Italy and I bought the PCE-AC68 from Amazon. The box says this card may be operated in Italy. My router is Technicolor TG789VAC v2 and I can only manually choose 36, 40, 44 and 48 channels. On these four channels the AC68 won't connect. If I let the router choose the channel it could choose channel above 48.
I noticed that the AC68 will connect to channels in the middle (56,60,64...) and will not connect to the rest (>100).
OS is Windows 10. I know there are some problems with...

PCE-AC68 not picking up 5GHz channels