All devices connect to WiFi but none can reach internet. Connecting via ethernet cable works fine?

All devices connect to WiFi but none can reach internet. Connecting via ethernet cable works fine?
Added (1). I have not made any changes to my home network. All my devices -- laptop, iPhone, iPad -- can connect to my home WiFi but when connected via WiFi, they cannot access internet. If I perform nslookup google.com, the DSN request times out. My wireless router is a Linksys E2100L. All computers connected to the router via ethernet cable can get to the internet just fine. Is it time to buy a new wireless router?

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