Question Ac 9260 5Ghz stuck on 20mhz?

[Pingo9]

Recently i had to replace the antenna cables since they broke one month before i was able to replace it. Meanwhile i had to format my computer.
I have a 200 Megabit/s connection and before that i was able to use all of it, almsot 25,6 Megabyte/s on download. Now, for some unknown reason, i can use more than half of it, 171Mb/s now and 14-16MB/s on donwload, wich is pretty bad. I wasted so much time to find a solution until yesterday when i discovered that my 5ghz wifi is stuck on a 20mhz channel bandwith, 40-80-160 doesn't show up how it used to be, the 2.4ghz has a "nerf" too. My router IS able to run a 160mhz channel.
I tried to send a ticket to intel but the system doesn't work so i can't do that.

I have no clue of what could be reason of this problem. It could be broke antenna, a bad anntenna cable, the wirless card itself or software, i don't know. what i know is that i don't have any ideas of what to do now.

I apologies for my bad english but it's not my native language

 

[Lutfij]

Did you replace the antenna with one that is meant to work with your wireless adapter? Is the wireless card on a laptop or a desktop? You're sure you ruled out BIOS updates and drivers from your checklist for troubleshooting?

 

[Pingo9]

Did you replace the antenna with one that is meant to work with your wireless adapter? Is the wireless card on a laptop or a desktop? You're sure you ruled out BIOS updates and drivers from your checklist for troubleshooting?

I didn't replace the antenna only the cable, it is a desktop and it's mount on a crosshait hero 6 wich has a mini pc slot under the i/o shield. Ye I've got all the updates even the bios and yesterday I formatted the Pc again with no improvement at all, same situation.