Electrs synchronisation

Hello greetings to the Umbrel community, I am new to the forum and this is my first query.
I have installed in Umbrel Home the Bitcoin Core tesnet3 as well as Electrs, the BC has downloaded the blockchain but Electrs has been trying to connect to the server for many hours and the bar has not even started, why does it take so long to connect? I need to connect it to make test transactions?
I have also downloaded Testnet4 and Signet but the Regnest one won’t download after several hours and I abandoned it.
Which one is the most suitable for testing?
Regards