Please, i have one WiFi device 'internet radio receiver' connected via WIFI. This device disconnects immediately when i connect computer to LAN with cable. 

After that the WiFi device is trying to reconnect. Connected and after 10s disconnects. 

It hapends with this two devices only. Others works together in LAN well.  

I checked for IP conflicts. All Is ok. 

To be sure i made IP reservation of both devices on DHCP server. 

No limit of connected devices. 

The WIFI device work well on anorher router, also connected to personal hotspot on my cell phone. 

Do you have any idea why It happend?

Thank you