Hello ameralys,
The best steps to take for an iPad that won't connect to a network as expected can be found in the Related Article above. If the behavior persists it may be a hardware issue, however, if the device information you've shared is accurate your iPad falls under obsolete products. You can find more details about vintage and obsolete products here: Obtaining service for your Apple product after an expired warranty - Apple Support
"About obsolete products
Products are considered obsolete when Apple stopped distributing them for sale more than 7 years ago. Monster-branded Beats products are considered obsolete regardless of when they were purchased.
Apple discontinues all hardware service for obsolete products, with the sole exception of Mac laptops that are eligible for an additional battery-only repair period. Service providers cannot order parts for obsolete products."
Regards.