The OP doesn't say if he has a desktop or a laptop computer.

 

If he has a laptop computer,  I would simply suggest buying another battery for it, as a spare, so when the power is cut off, he has two fully charged laptop batteries, which should give around 5 hours of use, if not more, depending on the laptop and battery size.  Some brands and models have high capacity batteries as an accessory that are twice the size of the standard battery, giving even longer time.  If the batteries are cheap generic brands, buy two spare batteries.    

 

For the internet, I would suggest a simple 4G USB dongle to go into the laptop.  It can be locked to a telco, or unlocked.   It's powered by the laptop USB port.  Leave the sim in the USB dongle and just put 20 baht on the account 59 days.   

On 8/31/2020 at 12:31 PM, BritManToo said:

Battery back up is the easiest.

Inverter 3k, battery 5k ...... lasts about 4 hours driving a TV, router & computer.

If you want a longer back up, buy more batteries.

 

 

Also need to buy a battery charger with this set up, to charge the battery up when the power comes back on.  

 

A good set up, but not so cheap.