if you use windows too, I remember from way back that windows made my network card to go to sleep(or some powersave move) at the windows shutdown, that make linux have issue with it.
I don’t remember what the exact issue was but I remember it was windows doing it at its shutdown to save power, because pcie network card can stay awake even with pc off so that computer can be woke up via network (‘Shutdown Wake-On-Lan’ or a ‘Wake on Magic Packet’)
windows made the card go to sleep and linux didn’t wake it up.
The modem chipset everywhere are a CPU in its own and a black box at that.
In your case it might go to sleep occasionally.
It did seem pretty consistent timing-wise. This is very possible.
if you use windows too, I remember from way back that windows made my network card to go to sleep(or some powersave move) at the windows shutdown, that make linux have issue with it.
I don’t remember what the exact issue was but I remember it was windows doing it at its shutdown to save power, because pcie network card can stay awake even with pc off so that computer can be woke up via network (‘Shutdown Wake-On-Lan’ or a ‘Wake on Magic Packet’) windows made the card go to sleep and linux didn’t wake it up.