I try to make a wifi bridge with my old router DLink Dir-615 and the Ubiquiti AP AC Pro. But when I configured the wireless connection at the Dir-615 with Lede 17.01 the message appears: Wireless is disabled or not associated.
Wireless is activated and it works with other Wifi networks. Both support the standards: 802.11 b/g/n.
LEDE 17.01 is no longer maintained or actively supported, you should upgrade to OpenWrt 19.07.
However, the D-Link DIR-615 in any variant cannot run OpenWrt 19.07 out of the box since it does not have enough flash and RAM. To save firmware space, a custom build of OpenWrt would be required, either from source or using the Image Builder. Depending on how much you like tinkering and your available time, it might be better to replace the device.
Is the Ubiquiti AP AC Pro also running OpenWrt? In this case, the best solution for a wireless bridge would be WDS.
Which wireless bridge configuration did you try?
Make sure this matches the AP's BSSID, or remove the option temporarily as an experiment.
While there is nothing wrong with this option:
it has no effect in client mode, where the channel is chosen by the AP. You can ignore it for now.
Instead, please check which channel is configured on the AP. Try to set it to a different one.
While trying to edit the channel on the AP, I couldn't log into it so I reseted the AP and set Channel to 11. After connecting to the AP it worked for like 2 seconds and then the message Wireless is disabled or not associated appeared again. -_-