I have a model MD786B/A iPad which will not do any updates is there anything I can do to stop hackers

That model number corresponds to a 2014 iPad Air 2 which can be upgraded/updated to the latest iPadOS 15.6.1.

IF that iPad is waaaay behind in iOS/iPadOS upgrades/updates, you will need to have access to a full computer, like a Mac or Windows PC, try either using the Finder on a Mac that has the newest macOS Catalina, or later macOS, installed OR with an older Mac with an older Mac OS, download and install the latest iTunes version ( or latest iTunes for Windows PC ), make sure the Mac or Windows PC is connected to the Internet, connect your iPad by the USB charge cable to the computer and let the iTunes application upgrade/update that iPad model, using the iTunes Software Update feature, to its current, maximum OS o12.5iPadOS 15.6.1.

Make sure your iPad is, at least, charged to 50% or greater to attempt this.

Also, make sure your iPad has, at least, between 6-8 GBs of free internal data storage space for downloading and installing a major iOS/iPadOS upgrade.

Also, make sure to do a backup of your iPad's data, prior to upgrading/updating.

Backup to Apple iCloud and/or a full Mac or Windows PC using the same iTunes app OR, if a newer Mac running macOS Catalina, or later, making a backup using the macOS Finder app.

If NO access to a Mac or Windows computer, you will have to seek help from a good friend or family member, with a full Mac or Windows PC, to help you out

OR

Search online to locate and call contact your nearest, “local” Apple Store location to try/attempt to make an appointment to get your Apple iPad upgraded/updated to its latest iPadOS 15 version.

Apple Store employees will be glad to help/assist you.

Best of Luck to You!

You have a first generation iPad Air.

Identify your iPad model - Apple Support

The first generation iPad Air, iPad mini2 and mini3 can only be updated to iOS 12.5.5.

Apple ended major update support for these models of iPad in September 2019 - although they continued to receive occasional “point” security updates until late last year. These devices cannot be updated to iPadOS 13 (or any later major versions of iPadOS) as the internal hardware does not meet the minimum technical requirements (CPU capabilities and available RAM) for newer versions of iOS/iPadOS.

Some App developers have dropped support for iOS versions preceding iOS 13.x for technical reasons (often because APIs or software libraries upon which they rely have been updated in the new version of iPadOS, making their App incompatible with earlier versions). 

Whilst many App titles remain compatible with your iPad, if you want or need to access to Apps requiring the most recent versions of iOS, you’ll need to consider replacement of your iPad with a newer or current model that supports iPadOS15.

As you cannot update your iPad Air1 system software - and therefore cannot benefit from recent security updates - your options to improve protection from malware and emerging threats is obviously limited. However, there are some measures that can substantially reduce your potential exposure to threats.

Due to the system architecture of iOS/iPadOS, unless jailbroken, your iPad is not susceptible to traditional malware infection per-se. However, as with all computer systems, there are still vulnerabilities and exploits to which you remain vulnerable. For older devices, no longer benefiting from regular security updates, the risk of an unpatched vulnerability being exploited increases.

The majority of threats to which you will be invariably exposed will surface via web pages or embedded links within email. Some of the better defences designed explicitly for iOS/iPadOS and Mac platforms, are not available for older versions of system software, but there are mitigations available that are usable with any computer.

Consider using a security focussed DNS Service in preference to automatic DNS settings. This can either be set on a per-device basis in system settings, or can be set-up on your home Router - and in so doing extends the benefit of this specific protection to other devices on your local network without additional configuration. I recommend using one of the following DNS services - for which IPv4 and IPv6 server addresses are listed:

Quad9 (recommended)

9.9.9.9

149.112.112.112

2620:fe::fe

2620:fe::9

OpenDNS

208.67.222.222

208.67.220.220

2620:0:ccc::2

2620:0:ccd::2

Cloudflare+APNIC

1.1.1.1

1.0.0.1

2606:4700:4700::1111

2606:4700:4700::1001

Use of the above DNS services will help to shield you from “known bad” websites and URLs - regardless of the installed operating system.

I hope this information and insight proves to be helpful to you - if only in better understanding the limitations of your current iPad and available threat mitigation that can be easily applied.