The much-hyped Apple iPad tablet, which was released on April 3, is – like most other first-generation devices – marred by certain issues, with the most prominent among them being the apparent trouble that users face while connecting to a Wi-Fi network.

Apple has already acknowledged the Wi-Fi-related issue with the iPad, noting in a post on its technical support site that “under certain conditions, iPad may not automatically rejoin a known Wi-Fi network after restart or waking from sleep.”

Apple also elaborated that the Wi-Fi connection problem may crop up with some third-party Wi-Fi routers which are dual-band capable – with most such routers either using a common network name for each network or using different security settings.

Recommending a solution to the Wi-Fi connection problem, Apple has advised the iPad users to craft separate Wi-Fi network names for each band and to retain consistency in their security settings.

Meanwhile, as per the company, over 300,000 iPads were sold in the US on its launch day. Moreover, Apple’s App Store recorded over 1 million application downloads; while the new iBookstore witnessed around 250,000 downloads of e-books, a day after the device went on sale.

Going by iSuppli estimates, nearly 7.1 million units of iPad will be sold round the world this year; with the sales figures likely to touch 14.4 and 20.1 million respectively in 2011 and 2012.