In source,
it is $1$ data link and $1$ network .. now as routers are in network layer
So in
$\text{Router1:}$At first, it goes to network layer like physical$\Rightarrow$DLL$\Rightarrow$network
(then again comes to physical like)$\Rightarrow$DLL$\Rightarrow$physical
$\text{Router2}:$
Physical$\Rightarrow$DLL$\Rightarrow$network$\Rightarrow$Dll$\Rightarrow$physical
Destination:
Physical$\Rightarrow$DLL$\Rightarrow$Network$\Rightarrow$TCP$\Rightarrow$Application
In both routers after computation in Network layer, it is coming back to physical again...
the reason is signals can only be transmitted with physical layer.
So, Network Layer$=4 \text{ Visit}.$
DLL$=6\text{ Visit}.$