Help receiving LN TXs via Muun Wallet, etc

Working through getting the Lightning Network functionality up and running on my Umbrel Full Node and am running into a bit of a challenge with the receive side of things.

So far the send is good. It also looks like I have sufficient liquidity to receive.

The issue is that when I try to say send myself 500 satoshis from my Muun wallet it fails.

When I send from my node to said Muun wallet it works.

One note is that when I send from my node to Muun the network fee is 5 satoshis.

When I try to send from my Muun to my node the fee is attempted to be only 1 satoshis.

Is that maybe a problem?

Any ideas on how to solve this?

Thank you very much!!!

You need more liquidity. In and out.
Just one single channel is not enough for a fluid way to make txs.
That channel is only outbound, you need also inbound channels and be well connected.
I explained this in the Getting Started guide with Umbrel, please read it. Also it explains how you can get liquidity.

Open more channels and if you can balance them.
I posted also a guide about how to use the ghetto swap method with known peers - that helps you very quickly to have liquidity on both sides (in and out).
But right now, if you already have a channel open FROM your node towards another one, means you have liquidity only for sending (outbound).
So you need somebody else to open towards your node a channel and in that moment you have INBOUND liquidity, so you can receive.
The rule is simple: more channels, more routes for your txs and others txs to be routed. Less channels, less routes.
Now, this doesn’t mean you will have to open like crazy 1000 channels in/out just to be able to send a stupid test tx. But with 2-3-4 channels with enough liquidity in and out is OK. Later in time, start adding more slowly.