So you need to make your router a router 
Go this way:
Assign the former 2800’s WAN IP address (189.87.255.186/30) to eth1 of your MT.
Create a bridge and give it your 2800’s former LAN address (201.73.106.33) - 201.73.106.34 is now free and can be used for other purposes as the remaining addresses from your /28 network.
(or assign 201.73.106.34) to the bridge and have .33 free for other purposes)
Create a default route to 189.87.255.185.
Add interfaces of your choice to the bementioned bridge and connect devices with puplic IPs in this subnet (201.73.106.34…201.73.106.38).
Cheers
-Chris