Your network diagram does not clearly show interface/port numbers between devices. Therefore, I am trying to guess as much as I can.
1.
On the right side of your Router1, I see its Int F0/1 is connecting to Int F0/1 of right-side Switch (on which you have two VLANs 300 and 400 configured):
Int F0/1 of right-side Switch should be configured as trunk port (allowed VLANs 300 and 400) and Int F0/1 of Router1 should be configured with two subinterface F0/1.300 and F0/1.400.
You need to assign IP addresses in subnets of VLAN 300 and 400 for subinterface F0/1.300 and F0/1.400 on Router1, for example 10.10.239.253/28 and 10.10.255.253/28, respectively. These are Relay Agent IP addresses in DHCP request packets.
2.
Next, you need to configure the IP address of DHCP server (here is Router0) under Router1's two subinterfaces F0/1.300 and F0/1.400 using ip helper-address IP_Address command.
The IP address of Router0 DHCP server you use here depends on L3 segment/network between your Router1 (Int F0/0 on the left side) and Router0.
Your network has 4 VLANs/subnets. On Router1, you already use F0/1.300 and F0/1.400 subinterfaces (in VLAN 300 and 400), therefore you have to assign an IP address in other VLANs (either VLAN 100 or 200) for Int F0/0 of Router1. Let us say we choose the VLAN 100 and create an subinterface F0/0.100 with IP: 10.10.207.253/28, then we have to configure Int F0/2 of left-side switch (connecting to F0/0 of Router1) to trunk VLAN 100 as well.
Now, the IP address of Router0 DHCP server we use for ip helper-address IP_Address command must be the IP address of subinterface F0/0.100 - 10.10.207.254. Because the relayed DHCP requests from Router1 is routed through VLAN 100 on left-side switch, then hit Router1 on its subinterface F0/0.100.
3.
Lastly, we need to ensure that Router0 knows how to send the traffic back to Router1 DHCP Relay Agent IP addresses (10.10.239.253 and 10.10.255.253) by adding static routes for them with next-hop IP is the IP address of Router 1 F0/0.100 subinterface (10.10.207.253).
4.
I do not put the configuration for Switches here, I assume they are good with all VLANs, trunk and access ports are configured properly.
The updated full configuration on Routers and Switches:
*********************
***** Router0 *****
*********************
!
ip dhcp excluded-address 10.10.207.253
ip dhcp excluded-address 10.10.239.253
ip dhcp excluded-address 10.10.255.253
!
ip dhcp pool 100
network 10.10.192.0 255.255.240.0
default-router 10.10.207.254
ip dhcp pool 200
network 10.10.208.0 255.255.240.0
default-router 10.10.223.254
ip dhcp pool 400
network 10.10.240.0 255.255.240.0
default-router 10.10.255.254
ip dhcp pool 300
network 10.10.224.0 255.255.240.0
default-router 10.10.239.254
!
interface FastEthernet0/0
description Left-side Switch
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.100
encapsulation dot1Q 100
ip address 10.10.207.254 255.255.240.0
!
interface FastEthernet0/0.200
encapsulation dot1Q 200
ip address 10.10.223.254 255.255.240.0
!
interface FastEthernet0/0.300
encapsulation dot1Q 300
ip address 10.10.239.254 255.255.240.0
!
interface FastEthernet0/0.400
encapsulation dot1Q 400
ip address 10.10.255.254 255.255.240.0
!
ip route 10.10.239.253 255.255.255.255 10.10.207.253
ip route 10.10.255.253 255.255.255.255 10.10.207.253
!
*********************
**Left-side Switch**
*********************
!
vlan 100
!
vlan 200
!
vlan 300
!
vlan 400
!
interface FastEthernet0/1
description Router0
switchport trunk allowed vlan 100,200,300,400
switchport mode trunk
!
interface FastEthernet0/2
description Router1
switchport trunk allowed vlan 100
switchport mode trunk
!
interface FastEthernet0/3
description PC_VLAN100
switchport access vlan 100
switchport mode access
!
interface FastEthernet0/4
description PC_VLAN200
switchport access vlan 200
switchport mode access
!
*********************
***** Router1 *****
*********************
!
interface FastEthernet0/0
description Left-side Switch
no ip address
duplex auto
speed auto
!
interface FastEthernet0/0.100
encapsulation dot1Q 100
ip address 10.10.207.253 255.255.240.0
!
interface FastEthernet0/1
description Right-side Switch
no ip address
duplex auto
speed auto
!
interface FastEthernet0/1.300
encapsulation dot1Q 300
ip address 10.10.239.253 255.255.240.0
ip helper-address 10.10.207.254
!
interface FastEthernet0/1.400
encapsulation dot1Q 400
ip address 10.10.255.253 255.255.240.0
ip helper-address 10.10.207.254
!
*********************
**Right-side Switch**
*********************
!
vlan 300
!
vlan 400
!
interface FastEthernet0/1
description Router1
switchport trunk allowed vlan 300,400
switchport mode trunk
!
interface FastEthernet0/2
description PC_VLAN300
switchport access vlan 300
switchport mode access
!
interface FastEthernet0/3
description PC_VLAN400
switchport access vlan 400
switchport mode access
!
Testing on Router0
Router0#ping 10.10.239.253
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.239.253, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/1/5 ms
Router0#ping 10.10.255.253
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.255.253, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/1/4 ms
PC in VLAN 300 (on the right side) can get IP address:
======
In this case, VLANs 300 and 400 are on the right side of the network, You should configure the IP addresses of 10.10.239.253 and 10.10.255.253 are default gateway IPs (Router1 subinterfaces) in DHCP IP Pool 300 and 400 on Router0.
======
I hope it is helpful.
