It'd probably help if you didn't turn off your modem at night and then simultaneously fire everything up the next morning.
When you reboot a modem, you're essentially rebuilding your connection to the headend at Cox. You may be assigned a new public IP address or you may not; however, every parameter of your WAN connection is rebuilt...including a routing table. However, you've also got tables in your home and your morning routine may be creating conflicts.
While your modem is rebooting, your router will lose its WAN connection. Once your modem is online, its new table and the router's table may not match. It may take a while to resync or you could force a resync by rebooting the router or...in your case...another reboot while the router is online.
You didn't mention doing this but if you reboot the router and don't remove power long enough, its capacitors may still have enough juice to retain the previous table. Furthermore, after the router reboots, it needs to rebuild its table with every already-connected device...that is, every device already having a previously-assigned private IP address from the router. You may or may not be having conflicts with your private IP addresses.
There's a lot going on during your morning routine. Why are you shutting down your modem: security, conservation, annoyance? Just shut down your router at night...that's what I do.
