Following https://openwrt.org/inbox/toh/d-link/dap-x1860?datasrt=unsupported%20functions I flashed a D-Link DAP-X1860.
It showed:
D-Link Repeater Recovery Mode
Upgrade complete!
Rebooting ...
Please note the led was blinking in red, not in orange, after I did what was described,
Enter recovery mode. (Hold RESET button, before plugin in the repeater, until orange power light starts blinking)
Then I changed the IP-address of my Ubuntu-PC from 192.1.0.51 to 192.168.1.51 and restarted the network.
http://192.168.1.1/ show the Apache 2 default page with Chromium and Firefox. I flashed with Chromium.
The LED shows a constant green LED, not blinking.
I can ping 192.168.1.1
$ ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.032 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.066 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=0.056 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=0.053 ms
--- 192.168.1.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3077ms
$ ip n s
192.168.1.51 dev enp1s0 INCOMPLETE
fe80::6629:43ff:fea5:1680 dev enp1s0 lladdr 64:....:80 router STALE
$ sudo ifconfig -a
enp1s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.1 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fdbb:7293:....:e3cd prefixlen 64 scopeid 0x0<global>
inet6 fdbb:7293:....:93e9 prefixlen 64 scopeid 0x0<global>
inet6 fe80::....:8718 prefixlen 64 scopeid 0x20<link>
inet6 fdbb:....::6f0 prefixlen 128 scopeid 0x0<global>
ether 70:....:12 txqueuelen 1000 (Ethernet)
RX packets 9314 bytes 564734 (564.7 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 20888 bytes 14734795 (14.7 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0