connection not possible when switching from LNC node to another node and back

[myxmaster]

Describe the bug

(Might be related to #1483, but not sure.)

When you are connected to a node via LNC, then switch to another node and then back to the LNC node again, Zeus cannot
connect and displays "Failed to connect the LNC client to the proxy server". Using the "Restart" button or killing the app fixes the
problem and Zeus will connect to the LNC node again.

The connect method in LNC class runs through fine (no error):

zeus/zeus_modules/@lightninglabs/lnc-rn/lib/lnc.ts

Lines 94 to 130 in e0125a6

	/**
	* Connects to the LNC proxy server
	* @returns a promise that resolves when the connection is established
	*/
	async connect() {
	// do not attempt to connect multiple times
	const connected = await this.isConnected();
	if (connected) return;
	NativeModules.LncModule.registerLocalPrivCreateCallback(
	this._namespace,
	this.onLocalPrivCreate
	);
	NativeModules.LncModule.registerRemoteKeyReceiveCallback(
	this._namespace,
	this.onRemoteKeyReceive
	);
	NativeModules.LncModule.registerAuthDataCallback(
	this._namespace,
	this.onAuthData
	);
	const { pairingPhrase, localKey, remoteKey, serverHost } =
	this.credentials;
	// connect to the server
	const error = await NativeModules.LncModule.connectServer(
	this._namespace,
	serverHost,
	false,
	pairingPhrase,
	localKey,
	remoteKey
	);
	return error;
	}

What happens, when the error occurs, is: BackendUtils.isConnected() keeps returning false until Zeus gives up:

zeus/stores/SettingsStore.ts

Lines 1212 to 1225 in e0125a6

	counter++;
	const connected = await BackendUtils.isConnected();
	if (connected) {
	clearInterval(interval);
	this.loading = false;
	resolve();
	} else if (counter > 20) {
	clearInterval(interval);
	this.error = true;
	this.errorMsg = localeString(
	'stores.SettingsStore.lncConnectError'
	);
	this.loading = false;
	resolve(this.errorMsg);

I made sure BackendUtils.isConnected() is really calling isConnected() in LNC class, so question is: why is it not possible to establish a connection when switching nodes like this?

Edit:
I can reproduce this issue with Zeus v0.8.0 on my physical device (Galaxy Tab S9+, Android 13) and emulator (Android Emulator Pixel 7 Pro, Android 14).
I can not reproduce it with Zeus v0.7.7 on my physical device (Samsung Galaxy S20+, Android 13).

Reproduce

Zeus version

v0.8.0

Node interface

LND (Lightning Node Connect)

Network

Clearnet

Device

Android Emulator Pixel 7 Pro

Device operating system

Android 14

Log output

No response

[BitcoinMechanic]

I have a similar issue just around LNC connected Zeus just timing out. I have to restart the app every single time I use it. It always connects reliably upon restart though.

edit: running grapheneOS, zeus v0.8.2, friend has exact same issue on iPhone with whatever version is on the app store.

[kaloudis]

Maybe the disconnect call isn't getting executed properly, or perhaps we have a system issue. Would be nice to get some more clarity.