Beryl GL-MT1300 user here
I recently noticed, in a hotel, that my router kept blinking green, even though internet works fine.
After investigating, it appears that the hotel's network blocks ICMP requests. I guess the router is trying to ping some host on the internet to check is internet is available, and failing to do so it wrongfully assumes that there's no internet.
On my laptop (Linux/Gnome) I had also a visual indicator to detect if internet is available (through a ping on 8.8.8.8). I modified it to also do an HTTP ping (https://www.hping.org/) before concluding that internet isn't available.
I think the router should implement something similar : it's very disturbing to see it blink green even though internet is working.