Why not use dynamic DNS? Then you don't need to worry about IP changes.
Keywords here are 'control' and 'security'
Eg. on the ERL connected to my VQ line, my ST IP address belongs to a group of Whitelisted IPs (for access to various services).
On the MikroTik that's connected to my ST line, I've Port Forwarding & VPN Server access done in similar fashion.
Never like to rely on DDNS and UPnP even when I was previously using consumer routers from Asus and D-Link (even though these don't have IP whitelist capability).