Please run the following commands (copy-paste the whole block) and paste the output here, using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have
ubus call system board; \
uci export network; uci export wireless; uci export firewall; \
head -n -0 /etc/firewall.user
I suppose that your client is in the lan zone and you want to access a device in iot zone.
Keep in mind that some broadcasts, like mdns, do not extend outside of a broadcast domain without certain configuration. You should be able to access them by using their address directly.