Lightning node setup to get fees strategy not working

Thank you in advance for reading this.

I have setup my node and I am helping some merchants to accept Bitcoin. My business model is to gain fees through the payments they get. To do that I have opened a channel from their node to my node, I have given them inbound liquidity (500k sats) and I setup my fees (1,000 sats fixed + 0.025%). My node is pretty well connected with Bitfinex, Voltage and some others with good liquidity both outbond and inbound, nevertheless the payment fails giving the following errors, even for small payment such as 1,000 sats:

If paid from bluewallet: API error: Payment failed. Does the receiver have enough inbound capacity? (code 10)

If paid from Muun: No route can be found.

When I try to lower fees, it works, but I need to put them these fees higher if I want my business plan to work. In any case I don’t understand why it does not work if I have a route with liquidity.

I am using Umbrel and Thunderhub to manage this.

Thank you once again and best regards,