There is many topic's, concerning DDNS. Quite a many of them are without final solution.
So here's one more.
DDNS has been checked/configured according to a folllowing help file.
https://wiki.teltonika-networks.com/view/Noip.com_DDNS_configuration
At the end of it, host was accessed through internet. Easy.
But, what if connection does not appear?
Connection to internet comes from SIM card.
DDNS configuration displays IP from noip.
From noip, "last update" time won't update at all.
Any ideas?
As a reference, I put the same SIM card with same noip settings to Telewell router.
From noip.com, I can see that TW has updated it's status to noip.com. ("last update" time will update within seconds)
Then I checked from an other network (phone) that I have an access to TW, through hostname, typed in to noip.com.