If https://canyouseeme.org/ says it can see your open port, then there is nothing wrong with the home hub settings.
What is more likely is that your app is not seeing your changed public IP address, which is why its not working.
Look at the webserver page, here is a screenshot from BI4, BI5 may be slightly different.
Make a note of the external WAN IP address.
Then visit https://www.whatismyip.com/ and check to see if the IPv4 IP address is the same as the one showing on the Blue Iris web server page.
If they are not the same, then your public IP address is not being updated and you need to check on the main BI page to make sure "Register IP address to assist with client app connections" is ticked as that allows the app to update your public IP address, using the licence key information that you entered into the app.
If you still have issues, then enter your current public IP address into the app, and see if that works, bearing in mind that this will change if the home hub loses power or is restarted.
The other thing you can do is to access the BI interface using a normal web browser, by entering the WAN address and port number into the address bar. This will load the UI3 web interface which will display all cameras.
My guess is that the power cut has simply resulted in a change of public IP adders, and you have not refreshed the server settings on the app. I use the old version of the app, as it works best with BI4.
