AFAIK most routers total the errors up over time (they are cumulative). Error stats normally only clear if reset or the router is restarted.
Mine will rack up over periods of weeks/months unless I reboot on all the routers that Ive had.
I've not heard of a router that resets after 2 days.. its normally in conjunction with your uptime figure.
If looking at someone stats then we divide the no of errors by the uptime figure.
So with yours it would be
1 days 2 hours 8 min 41 sec = approx 26 hrs = 93600 seconds
of which 1148 Errored Seconds is perfectly acceptable.
Obviously if all ES's came at once then its more serious than spread out over time.
Hope that makes sense.
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PS
The bottom figure Up Time 121:44:50 is actually the time your router has been on for.
Most routers will display 2 'up times'.. one is the 'switched on', the other is the 'online'. We ignore the switched on time.