Usually this is caused by Kodi hanging or crashing at shutdown and not writing wakeup information.
Unfortunately on your old LE 11 system pasting logs does not work any more because http://ix.io service was suspended. To upload it manually do (e.g.):
You may consider updating to LE12.
Looking at the HW side the RTC battery may be dead. Having an older PC it is always worth just to replace the CR2032 on the motherboard. Remember to reset the BIOS/firmware settings to default after that.