Vextra Security review for MO: Country Blocker & IP Block

Seems to be too good to be true, free app. I could even pay. I added about 30 countries to block, click save and end up with non saved. then added 6 countries and it saved. so, there are over 240 countries in the world and I wanted to sell in my country only by blocking others. There is no whitelisting for one country and blocking doesnt work for more than may be 15-20. Also the selection of countries in the available list is cumbersome, no multi selection, only one by one. can it be improved at all?