Looking at imagebuilder and the latest I get is v4.1.0 and I am running stable 4.2.3
root@debian02:~/imagebuilder/glinet# git tag | grep ax1800
v3.206_ax1800
v3.207_ax1800
v3.208_ax1800
v3.212_ax1800
v3.213_ax1800
v3.214_ax1800
v4.1.0_ax1800
root@debian02:~/imagebuilder/glinet#