I have two new D53G-5HacD2HnD ( Chateau LTE12 ).
Both of them have identical configuration.
At first everything looks fine, but second have some weird things.
At routes I have two dynamic default 0.0.0.0/0 LTE1.
But in terminal show normal.
Check your firmware first, both RouterOS and modem’s.
No idea, but sometimes LTE interfaces end up with unexpected /ip/dhcp-client, or /interface/detect-internet if enabled can cause weird things. Also, you make want to make sure you’re only using one APN (e.g. while the list may allow multiple APNs, that be a bad idea if carrier doesn’t support – so creating a NEW “APN Profile” with “fresh” settings may also help.
Could also very likely be a bug - so more things to “try”.
check … both same last stable
configuration verbose
/interface lte apn
set [ find default=yes ] add-default-route=yes apn=internet authentication=none default-route-distance=2 ip-type=auto name=default use-network-apn=yes \
use-peer-dns=yes
You might want to find the actual APN to use, if there is one. But since you have “Use Network APN” that mean essentially “use SIM card for APN”.
You should try disabling “Use Network APN”. In fact, very latest v7.2rc4 has a release note that it’s disabled by default.
Serious question: why is it better to set “Use network APN” to “no”?
I try to do that … nothing change … still remain two dynamic default.
And like “infabo” ask … why to do that ?
APN is essential to properly work … in that case I need to manually put APN … which will be the same.
Well, it wasn’t working with it set to “yes”, idea was simple to try no 
Maybe some else no mores than me, but AFAIK “Use Network APN” being enabled tells the Mikrotik to ignore its value of APN (e.g. “internet”), and instead use the SIM card’s value. But sometimes your account/plan, or you have old SIM, etc. the value on the SIM card may be wrong or maybe not read right by MBIM/etc.
I’m not the expert on SIM cards, but AFAIK they can store the APN when programmed by the carrier. The SIM card itself may be subtly different, even if from same carrier.
Now since a lot of carrier to just take any APN or the default “internet” – so all this may have nothing to do with your problem – just suggestions. If so, perhaps try 7.2rc4 just to see if that changes what happens, without or with “Use Network APN”. And, perhaps trying a different SIM card in the unit, e.g. swapping them may be another approach to troubleshooting this…
This very well may be a bug, so maybe a report to Mikrotik – just that takes a while sometimes – why I can only suggest some things to try.
I would swap SIM cards and see if that “swaps” the issue to the other device too.