The configuration options list is still incomplete.
I have tested it as well and noticed that sending multiple more messages to get to port forwarding rules settings might be tricky, as the further messages may simply stop coming.
To make finding the rule faster, try sending the following message:
Replace <n> with number starting from 6 as there should already five preconfigured rules.
Returning messages should contain options specific to the rule, including name, in the following format:
- <router_password> firewall.cfg333333.option=value
You need to find cfgxxxxxx, which corresponds to the rule you want to disable and then send the following message:
- <router_password> firewall.cfgxxxxxx.enabled=0