One subnet does not see another?

Question

Computer networks

Good afternoon. There is an organization. Main building. It has a local network range of 10.10.0.0, a mask of 255.255.255.0. There is a remote branch with its own LAN, 172.16.3.0, subnet mask 255.255.0.0. We don't see them. And they see us. What could be the reason?
Another question - what kind of routers would you recommend relatively inexpensive, for organizing VPN tunnels between branches. Any of the Mikrotiks?

Answer 1

linkmeup.ru/sdsm
start here

Answer 2

1) Little information, many options. Basically there is no understanding of the term "see".
What kind of equipment, how is it configured, how do you check?
2) Some kind of Mikrotik.

Answer 3

As part of telepathy, the route from the 172.16 network towards the 10.10 network passes through NAT, which is why the 10.10 network simply does not know anything about 172.16.
PS: why subnet 172.16.3.0 with the sixteenth mask when it should be with the 24th? Typo?