The Teredo error may be coincidental but go into Device Manager by going Start - type devmgmt.msc and press enter.
Click on View/Show hidden devices and check to see if you have a yellow alert next to Teredo Tuneling.
If you have, follow these steps to reinstate it -
1. As an administrator from the Cmd Prompt, type then press Enter after each of these commands :-
2. netsh
3. int teredo
4. set state disabled
5. Open Device Manager/View/Show hidden devices > right click on Teredo Tunneling Pseudo-Interface and select Uninstall
6. Open the Cmd Prompt as an administrator again and type then Enter these cmds :-
7. netsh
8. int ipv6
9. set teredo client
10. Open Device Manager/Action/Scan for new hardware.
11. Then select Show hidden devices from the View menu.
It should now display without the yellow alert.
What security programs do you have installed ?
If those steps don't resolve the router problem then I would suggest disconnecting the printer and NAS cables and rebooting the router to see if they will then reconnect.
You should also be aware of this article -
https://www.symantec.com/blogs/threat-intelligence/vpnfilter-iot-malware