Serveraction failed network xhr preview empty

Hello everybody,
thank you in advance for your time.
I’ve a php project with mysql database in a cheap hosting.
Connection test with db ok, I can even insert table from wappler.
When I try to do a server connection to simply read a table:



I’ve tried with firefox same result.
I’ve tried to change localhost with the IP adress of remote db but nothing.
As you can imagine I’m a beginner and I’m sure I’m missing something very basic.
Thanks,
Nando.