This might be why : to be honest I have never run into that issue, kind of why i didn't say anything ... so i did a search below might be why......
https://forum.armbian.com/index.php?/announcement/1-1-check-power-supply-check-sd-card-and-check-other-people-experiences/and the images off Avalon site have the IP set to 192.168.0.100
you have to set the network card on the PC your trying to access the controller on, to 192.168.0.1 hit the second line on your networks card UI after you set the ip don't worry about setting up the other lines just the first two lines.. then hit ok then go to any Internet Browser an type 192.168.0.100 and change in network setting in the Avalon ui you see not the openwrt you might normally see . change that to 192.168.
1.100
notice the red 1 that's kind of a big deal from 0 to 1 then reset your network card back by setting it back to defaults then go to any Internet Browser an type 192.168.
1.100 that should do it, can't say other wise .
having the wrong ip might be why it seem to not load right.