Or to add nodes right now without restarting:
lncli connect (pubkey)@(host):(port)
Find large nodes from 1ML.com or Amboss.space
No restart required in that case
This was the reason why the graph was not syncing in my LND setup too.
Once I manually added peers from Amboss.space with the above setup the graph was synced in few minutes.
After some time though, the peers were disconnecting and I had to reconnect with new peers. So may be that is something you should check @Z_MBFM