RT-AC59U V2 5Ghz wifi problem

[Ironman]

Hello Guys,

I have an Asus RT-AC59U V2 router with the following issue:
There is only one device on my network that is able to connect via 5Ghz wifi. When I trying to move files to this device with the help of Filezilla(ftp) the router goes down, it becomes "death". I need to restart it to make it usable again. I changed the channel of the 5ghz signal but still not works. When I use 2.4 ghz and do the same process everything works fine. I am not an expert of this
Any suggestions or ideas?

Thanks,
Have a nice day for everyone

 

[degrub]

are the files on a USB stick plugged into the router ?

 

[Ironman]

Hi,
No, files are stored on my Desktop that is connected to my LAN. It has a filezilla server.
THX