Routing issue or ISP issue

Hi
I have at 2 different locations in the same town a fibre connection from the same provider.
The issue I am facing is that both my Mikrotik routers at each location cant access each other or any dnatted traffic. (no traffic is reaching the routers in any direction from the ISP network)
I am getting a WAN IP address from the same DHCP server both ends and the IP range both sides are 156.x.x.x/26

From any other network my dnat traffic work (and any other traffic reach my routers) so I am thinking that because the IP address I get for my WAN are basically
the same network both sides my router doesn’t know how to route this accordingly to reach the other end over the internet.

The service provider says they don’t block anything and the problem is on my side. Do you think they are blocking accessing IP’s
on and from the same network or do I need to create source NAT or any other rules to make this work.

It depends if the addresses are in the same /26 subnet or not - if they are then layer2 port isolation, or similar, could well be an issue. What do you get if you try ping and traceroute from one router to the other, and again in the other direction?