After hours of testing i can not connect to any 5ghz Network.

Status always says 5ghz: "No Signal"

I tried switching channels 36, 40, 100

I tried disabling security
The 5ghz Led only lights up on reboot and never lights up again whatever i do.

I can find the 5ghz Network with Wireless Scanner from RE580D Andmin interface at full Signal.

2.4ghz is working as expected.

Extend Network is disabled for 2.4 and 5ghz.

5ghz is not working even if i disable 2.4 connection.

RE580D has the lates firmware.

VR900v has the lates firmware.

Fritzbox has the lates firmware.

Distance to Router approx 5m.

Not connecting to Fritzbox 7460 and TP-LINK VR900v on 5ghz. 

All other devices iphone, ipad, Macbook, Alexa, Samsung Tv can connect to the 5ghz Network.

VR900v setup.

• SSID: ALICE
• Security: WPA / WPA2 Personal
• Version: WPA2-PSK ( AES )
• Password: xxx
• Mode: 802.11a/n/ac mixed
• Channel: Automatic
• Channelwidth: Auto
• TX: High

RE580D setup:

• SSID: ALICE
• Security: WPA2-PSK
• Password: xxx

The reboot log looks like this:

0 days 00:00:04      OTHERS     INFO    Booted the system. 
0 days 00:00:04      DHCPS      INFO    DHCP server started 
0 days 00:00:07      DHCPS      INFO    Received a request packet from 70:4D:7B:28:C8:B0 
0 days 00:00:07      DHCPS      INFO    Sent an NAK packet 
0 days 00:00:07      DHCPS      INFO    Received a discovery packet from 70:4D:7B:28:C8:B0 
0 days 00:00:09      DHCPS      INFO    Provided an offer for the client with ip 192.168.0.100 
0 days 00:00:09      DHCPS      INFO    Received a request packet from 70:4D:7B:28:C8:B0 
0 days 00:00:09      DHCPS      INFO    Sent an ACK packet to 192.168.0.100 
0 days 00:00:12      WIRELESS   ERROR   5G failed to connect to the front end: SET_SSID 3, 0. 
0 days 00:00:13      WIRELESS   INFO    2.4G successfully connected to the front end. 
0 days 00:00:13      WIRELESS   INFO    Key exchange between 2.4G and the front end started. 
0 days 00:00:13      WIRELESS   INFO    Key exchange between 2.4G and the front end succeeded. 
0 days 00:00:16      DHCPC      INFO    Sent a detection for DHCP. 
0 days 00:00:19      DHCPC      INFO    Sent a detection for DHCP. 
0 days 00:00:19      DHCPC      INFO    Received a DHCP offer:Server ID is 54.Assigned IP address is 192.168.1.100 
0 days 00:00:19      DHCPC      INFO    Sent a request for DHCP. 
0 days 00:00:21      DNS        ERROR   DNS probing failed, DUT can not get a dns server. 
0 days 00:00:21      NTP        ERROR   NTP detection failed. 
0 days 00:00:21      DHCPC      INFO    DHCP obtained an IP address 192.168.1.100 
0 days 00:00:21      DHCPS      INFO    DHCP server stopped 
0 days 00:00:26      DNS        INFO    DNS detection succeeded. 
0 days 00:00:26      NTP        INFO    NTP detection succeeded. 
0 days 00:03:45      WIRELESS   INFO    2.4G front end exited: 0, 7 
0 days 00:03:48      WIRELESS   ERROR   2.4GHz disconnected from the front end. 
0 days 00:03:49      DHCPS      INFO    DHCP server started 
0 days 00:03:52      WIRELESS   INFO    2.4G successfully connected to the front end. 
0 days 00:03:52      WIRELESS   INFO    Key exchange between 2.4G and the front end started. 
0 days 00:03:52      WIRELESS   INFO    Key exchange between 2.4G and the front end succeeded. 
0 days 00:03:52      DHCPS      INFO    Received a request packet from 70:4D:7B:28:C8:B0 
0 days 00:03:52      DHCPS      INFO    Sent an NAK packet 
0 days 00:03:52      DHCPS      INFO    Received a discovery packet from 70:4D:7B:28:C8:B0 
0 days 00:03:54      DHCPS      INFO    Provided an offer for the client with ip 192.168.0.100 
0 days 00:03:54      DHCPS      INFO    Received a discovery packet from 00:14:EE:08:D0:6A 
0 days 00:03:56      DHCPS      INFO    Provided an offer for the client with ip 192.168.0.101 
0 days 00:03:57      DHCPS      INFO    Received a request packet from 70:4D:7B:28:C8:B0 
0 days 00:03:57      DHCPS      INFO    Sent an ACK packet to 192.168.0.100 
0 days 00:03:57      DHCPS      INFO    Received a discovery packet from 00:14:EE:08:D0:6A 
0 days 00:03:57      DHCPS      INFO    Provided an offer for the client with ip 192.168.0.101 
0 days 00:03:57      DHCPS      INFO    Received a request packet from 70:4D:7B:28:C8:B0 
0 days 00:03:57      DHCPS      INFO    Sent an ACK packet to 192.168.0.100 
0 days 00:03:57      DHCPS      INFO    Received a request packet from 00:14:EE:08:D0:6A 
0 days 00:03:57      DHCPS      INFO    Sent an ACK packet to 192.168.0.101 
0 days 00:03:58      DHCPS      INFO    Received a request packet from 4C:EF:C0:64:B7:2B 
0 days 00:03:58      DHCPS      INFO    Sent an NAK packet 
0 days 00:04:00      DHCPC      INFO    Sent a detection for DHCP. 
0 days 00:04:03      DHCPC      INFO    Sent a detection for DHCP. 
0 days 00:04:03      DHCPC      INFO    Received a DHCP offer:Server ID is 54.Assigned IP address is 192.168.1.100 
0 days 00:04:03      DHCPC      INFO    Sent a request for DHCP. 
0 days 00:04:05      DHCPC      INFO    DHCP obtained an IP address 192.168.1.100 
0 days 00:04:05      DHCPS      INFO    DHCP server stopped 
0 days 00:05:17      WIRELESS   ERROR   5G failed to connect to the front end: ASSOC 1, 22. 
0 days 00:05:17      WIRELESS   ERROR   5G failed to connect to the front end: SET_SSID 1, 0. 
0 days 00:05:40      WIRELESS   ERROR   5G failed to connect to the front end: ASSOC 1, 22. 
0 days 00:05:40      WIRELESS   ERROR   5G failed to connect to the front end: SET_SSID 1, 0. 
0 days 00:08:24      WIRELESS   ERROR   5G failed to connect to the front end: ASSOC 1, 22. 
0 days 00:08:24      WIRELESS   ERROR   5G failed to connect to the front end: SET_SSID 1, 0.