Can ipad model md786ll/b be updated beyond version 9.3.4?

The model number corresponds with a first generation iPad Air.

The iPad Air1 can be updated to iOS 12.5.5.

These support pages outline both the available methods by which the update can be performed - and troubleshooting should you experience difficulties:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

iOS update and restore errors – Apple Support

Be aware that your iPad may be too far behind the current version to be updated directly from iPad settings. As such, you will likely need to use a computer to perform the update. You will need access to either a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of MacOS). Ensure that your installed version of iTunes has been updated to the most recent version; the essential device drivers are included.

Download and use iTunes for Windows – Apple Support

Update to the latest version of iTunes – Apple Support

Update software on iPhone, iPad or iPod touch in iTunes on PC - Apple Support

You should note that for your iPad to install an available update, its battery must be charged to at least 50% capacity - and/or be connected to its Power Adapter. Similarly, the iPad can only be updated over a standard WiFi connection - or be updated by a PC or Mac using iTunes or Finder - over a USB connection.

That model number looks like a first generation iPad Air. But to be sure, could you look at the back of the iPad, and you will find a 4-digit number that starts with an A, then 4-digits. Please report that to be sure. A first generation iPad Air should be able to update to iOS 12.5.5.

The Model A1474 is a first gen iPad Air and will update to iOS 12.5.5. Follow the steps that LotusPilot provided.