You can check the cpu temperatures on some Linux terminal by typing the follow:
CPU temperatures of Intel PC CPUs are often specified up t 105°C.
I dont know the specification of gl used CPUs, a 90°C should be no problem by any CPU vendor. It can be, temperatures up to 60°C are the best.
From my point of view, the hardware of gl routers dont have problems.
Actual firmware can found on follow (It can be the Link to download section are not available since some days on gl website by navigation menue, a can still found by google …)
For known bugs, you can check the follow: