For both me and @xize11 the temperature was well above 70 degrees. For me it hovers at around 76 with the fan off. I have a wireguard server + adguard home running only. @xize11 Had 80.
So at least for us the fan is a must, to keep the temperature in a good range for extended life.
You can check the following 2 graphs about electrolytic caps life vs temperature:
Graphs from here: