How to use Electrum with a local regtest network? The problem

I have a regtest network running in 127.0.0.1:18443.
I can access to regtest with user:123.
I would like to use Electrum (v4.0.2) with my local regtest but I cannot realize how to do that.

What I tried
When I run:
electrum --regtest

The Electrum console opens as expected but the status is not connected:

My ~/.electrum/regtest contains:
{
    &quot;auto_connect&quot;: false,
    &quot;blockchain_preferred_block&quot;: {
        &quot;hash&quot;: &quot;0f9188f13cb7b2c71f2a335e3a4...........a11466e2206&quot;,
        &quot;height&quot;: 0
    },
    &quot;check_updates&quot;: false,
    &quot;config_version&quot;: 3,
    &quot;dont_show_testnet_warning&quot;: true,
    &quot;gui_last_wallet&quot;: &quot;/home/xxx/.electrum/regtest/wallets/default_wallet&quot;,
    &quot;is_maximized&quot;: false,
    &quot;oneserver&quot;: false,
    &quot;recently_open&quot;: [
        &quot;/home/xxx/.electrum/regtest/wallets/default_wallet&quot;
    ],
    &quot;rpcpassword&quot;: &quot;123&quot;,
    &quot;rpcuser&quot;: &quot;user&quot;,
    &quot;server&quot;: &quot;127.0.0.1:18443:s&quot;,
    &quot;show_addresses_tab&quot;: true
}


I changed rpcpassword and rpcuser with the user:pass of my local regtest, but I'm still unable to connect Electrum with my local network.
My questions

What am I doing wrong?
What does the &quot;s&quot; mean in 127.0.0.1:18443:s?
What's running in 127.0.0.1:51002?
Electrum doesn't connect directly to Bitcoin nodes. Instead it connects to Electrum servers using the Electrum protocol. These servers run Bitcoin nodes and additional Electrum server software in order to provide the data that Electrum actually needs to operate. So you need to be running an Electrum server software that connects to your node and then connect Electrum to that Electrum server.
Some Electrum server software:

Electrum Personal Server: EPS is designed for use with a single Electrum wallet and is probably the easiest to get an Electrum wallet connected to a full node
Bitcoin Wallet Tracker with Electrum plugin: BWT is like EPS but does more stuff and isn't just limited to Electrum
ElectrumX: ElectrumX is the official Electrum server software. It is a full fledged Electrum server software that is intended to be used by any connecting Electrum wallet. As such, it indexes the entire blockchain. If you want to do experimentation with the Electrum protocol, you may want to use this.
Electrs: Like ElectrumX but written in Rust.