First ipns ? I guess you meant ipfs ?
This is likely that thoses nodes are behind restrictive nat (no upnp for example) and thus can’t be dialled from the outside, ideally autonat would setup a relay to fix this, but relays aren’t so great for now (not too many nodes relaying) it’s not enabled by default. See more there : When I pin a file on my IPNS Desktop it should first check if port 4001 is unblocked - #2 by Jorropo