Two different MQTTs

Configuration
1

Hello, first of all say Welcome to all. I am a new member and hope to learn and share a lot with you.
My question has been there in 2016, but I want to know if the issue changed. My question is:

I need to have local mosquitto MQTT running and also have an online MQTT broker to access externally to several sensors, due to the fact i can’t access my HA because I am behind a CGNAT (no public IP).
Is there any possibility to have this, or any other feasible solution?
My MQTT broker is a free plan because I only need 3 sensors data, I don’t know if it has a bridge option…and if yes…it won’t work because I understand to bridge the data to local broker the IP-URL should be publicly accessible and it isn’t.

Any suggestions??

Thank you.
Luis

2

Does your provider give you a real IPv6 address?

3

I haven’t done it myself, but surely a script could be written to subscribe to the topics you care about on your cloud broker, and re-publish those messages to your local broker.

Some googling later…

I think this is what you want:
http://www.steves-internet-guide.com/mosquitto-bridge-configuration/

4

I have used this for years to bridge a public MQTT and a private MQTT