yall google does not work anymore on old 3ds!! i haven't tried yahoo! yet so might be an alternative to google here
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on new 3ds google doesn't work if you enable mobile pages and yahoo was broken since forever iirc
According to the netsurf-3ds github, the 3ds web-browser doesnt support the newer ssl required by most websites. some homebrewing might be your fix!
yahoo was always broken ;D