bostr makes Nostr usable on mobile... I run my own instance with it.

Some run instances to spam tons of relays at once. You are likely getting write blocked by using it

relays can use whatever backend mechanism they want to coordinate with each other. might be useful for blocking spam on public relays. email servers already do this with spamhaus, although they falsely block my email server ip range which is annoying.

Any nips that have relays sharing info with some kind of dht?

You would first need to define what would actually be shared. Not sure I would trust anything from a dht, some random person could just say “block these ip ranges”. That would not be useful.