Multipart payments should work by default since LND version 0.13 (https://lightning.engineering/posts/2021-06-17-lnd-v0.13/) . Seems like you had _just_ enough capacity, but your 2 peers are also not very big nodes, making it too hard for LND to find a path, which caused the payment to fail. In order to reliably receive payments , you would need between 5 and 10 balanced channels with top-500 nodes.