Perhaps a AT&T router and a Linksys router? If you have two routers both acting as routers then there will be problems.
Normal connectivity is generally as shown in the following line diagram:
ISP ----> Modem ----> Router ----- Ethernet cable ---- > wired devices and ~~~~ wireless ~~~~> wireless devices.
Sometimes the modem and router are combined.
Take a closer look at both the AT&T "router" and the Linksy. There should be model information plates/labels on each.
Routers often have logs that capture network events. However those logs may need to be enabled.
Who has full admin rights to the router(s)? You will need help from that person.
Yes: Run "ipconfig /all" then copy & paste the results into your post.
Do the...