Did you check the LND logs?

This past week I set up a new Start9 node, and LND would NOT connect to any peers to sync the chain. A full week went by and it just kept giving the same log error.

I finally resolved it by manually adding it as a peer to my primary node. Once LND had one peer to talk to, it was able to sync within a few hours. Simple.

Maybe it's the same issue you're having? If so, you can add my node as a peer if you want. Just DM me.

Also, I had tons of issues with LND syncing when I was using one of Start9's raspberry Pi nodes from a few years back. It was not powerful enough, and the Start9 team told me so straight up. That's probably why they stopped selling those low powered machines. Can you imagine if we were trying to run BCH nodes?! Fucking nightmarish.