There are many bars and restaurants in OSJ with Wi-Fi. There's even a free Wi-Fi hot spot at Plaza de Colon.
We have a hot spot feature with T-Mobile and have everything in our apartment in OSJ set up on it. We have complete internet access and pay something like $80/mo for all three phones, two TVs, tablets and computers, with unlimited voice and texting. There are dozens of channels that don't count on the data, including premium channels. We watch Netflix all day and don't pay anything for data. My property manager (who lives in OSJ J says Claro is the best for internet alone in the San Juan metropolitan area, but we got a better deal, all considered with T-Mobile.