I cannot find a howto for flashing there.
I have theGL-B1300 now and it looks like, I have the newest stock-firmware. It says 2.272
https://dl.gl-inet.com/firmware/b1300/v1/
qsdk-b1300-2.272.bin16340KLast modified: Tue Sep 11 2018 04:42:38 GMT+0200
But in the advance section I see Chaos Calmer 15.05.1, so this is 3 years old.
I need a wireless bridge, which I will ask in another thread.