Please find the configuration as follows:

N3048

!Current Configuration:
!System Description "Dell Networking N3048, 6.2.0.5, Linux 3.6.5-1289203e"
!System Software Version 6.2.0.5
!
configure
vlan 2-4
exit
vlan 2
name "camera"
exit
vlan 3
name "pabx"
exit
vlan 4
name "wireless"
exit
hostname "sw_L3"
slot 1/0 3 ! Dell Networking N3048
stack
member 1 4 ! N3048
exit
interface out-of-band
ip address 192.168.254.10 255.255.255.0 192.168.254.1
exit
ip routing
ip helper-address 192.168.1.5
interface vlan 1
ip address 192.168.1.1 255.255.255.0
ip netdirbcast
bandwidth 10000
exit
interface vlan 2
ip address 192.168.2.1 255.255.255.0
bandwidth 10000
exit
interface vlan 3
ip address 192.168.3.1 255.255.255.0
bandwidth 10000
exit
interface vlan 4
ip address 192.168.4.1 255.255.255.0
bandwidth 10000
ip helper-address 192.168.1.5 dhcp
exit
ip default-gateway 192.168.1.2
ip route 192.168.4.0 255.255.255.0 192.168.1.2
username "admin" password 51a32d722dd3b81772a68c7449d5e62d privilege 15 encrypte
d
dhcp l2relay
!
interface Gi1/0/39
switchport access vlan 3
exit
!
interface Gi1/0/40
switchport access vlan 3
exit
!
interface Gi1/0/41
switchport access vlan 4
exit
!
interface Gi1/0/42
switchport access vlan 4
exit
!
interface Gi1/0/43
switchport access vlan 2
exit
!
interface Gi1/0/44
switchport access vlan 2
exit
!
interface Gi1/0/45
switchport mode general
switchport general allowed vlan add 2
switchport general allowed vlan remove 1
switchport trunk allowed vlan 1,3-9,11-19,21-4093
exit
!
interface Te1/0/1
switchport mode trunk
switchport trunk allowed vlan 1-4
exit
!
interface Te1/0/2
switchport mode general
switchport general ingress-filtering disable
switchport general allowed vlan add 2-4 tagged
switchport general allowed vlan add 1 tagged
switchport trunk allowed vlan 1-4
exit
snmp-server engineid local 800002a2033417ebfe05f8
snmp-server community "public" rw ipaddress 192.168.254.254
exit

Switch 2048

!Current Configuration:
!System Description "Dell Networking N2048P, 6.2.0.5, Linux 3.6.5-1289203e"
!System Software Version 6.2.0.5
!
configure
vlan 2-4
exit
vlan 2
name "Camera"
exit
vlan 3
name "PABX"
exit
vlan 4
name "Wireless"
exit
hostname "sw_L2"
slot 2/0 9 ! Dell Networking N2048P
sntp broadcast client enable
clock timezone 4 minutes 0
stack
member 2 9 ! N2048P
exit
ip routing
ip helper-address 192.168.1.5
ip helper-address 192.168.1.55
interface vlan 1
ip address 192.168.1.3 255.255.255.0
exit
interface vlan 2
exit
bandwidth 10000
interface vlan 3
exit
interface vlan 4
ip netdirbcast
bandwidth 10000
exit
ip route 0.0.0.0 0.0.0.0 192.168.1.2
username "admin"
dhcp l2relay
dhcp l2relay vlan 4
!
interface Gi2/0/1
switchport access vlan 3
switchport trunk allowed vlan 1-29,31-4093
exit
!
interface Gi2/0/2
switchport access vlan 3
exit
!
interface Gi2/0/3
switchport access vlan 3
exit
!
interface Gi2/0/4
switchport access vlan 3
exit
!
interface Gi2/0/5
switchport access vlan 3
exit
!
interface Gi2/0/6
switchport access vlan 3
exit
!
interface Gi2/0/7
switchport access vlan 3
exit
!
interface Gi2/0/8
switchport access vlan 3
exit
!
interface Gi2/0/9
switchport access vlan 3
exit
!
interface Gi2/0/10
switchport access vlan 3
exit
!
interface Gi2/0/11
switchport access vlan 3
exit
!
interface Gi2/0/12
switchport access vlan 3
exit
!
interface Gi2/0/13
switchport access vlan 3
exit
!
interface Gi2/0/14
switchport access vlan 3
exit
!
interface Gi2/0/15
switchport access vlan 3
exit
!
interface Gi2/0/16
switchport access vlan 3
exit
!
interface Gi2/0/17
switchport access vlan 3
exit
!
interface Gi2/0/18
switchport access vlan 3
exit
!
interface Gi2/0/19
switchport access vlan 3
exit
!
interface Gi2/0/20
switchport access vlan 3
exit
!
interface Gi2/0/21
switchport access vlan 3
exit
!
interface Gi2/0/22
switchport access vlan 3
exit
!
interface Gi2/0/23
switchport access vlan 3
exit
!
interface Gi2/0/24
switchport access vlan 3
exit
!
interface Gi2/0/25
switchport access vlan 3
exit
!
interface Gi2/0/26
switchport access vlan 3
exit
!
interface Gi2/0/27
switchport access vlan 3
exit
!
interface Gi2/0/28
switchport access vlan 3
exit
!
interface Gi2/0/29
switchport access vlan 3
exit
!
interface Gi2/0/30
switchport access vlan 3
exit
!
interface Gi2/0/31
switchport access vlan 4
exit
!
interface Gi2/0/32
switchport mode general
switchport general pvid 4
switchport general allowed vlan add 4
switchport general allowed vlan remove 1
switchport access vlan 4
exit
!
interface Gi2/0/33
switchport access vlan 4
exit
!
interface Gi2/0/34
switchport access vlan 4
exit
!
interface Te2/0/1
switchport mode general
switchport general ingress-filtering disable
switchport general allowed vlan add 2-4 tagged
switchport general allowed vlan add 1 tagged
switchport trunk allowed vlan 1-2,4-4093
exit
!
interface Te2/0/2
switchport access vlan 4
exit
snmp-server engineid local 800002a203f48e3806c0a6
exit

Please let me know if there is anything missing in order for the VLANs to communicate each other plus the clients to access the internet through gateway 192.168.1.2

My N3048, Gi1 is connected to the firewall (192.168.1.2) and this port belongs to default VLAN

My new configuration as follows:

!Current Configuration:
!System Description "Dell Networking N3048, 6.2.0.5, Linux 3.6.5-1289203e"
!System Software Version 6.2.0.5
!
configure
vlan 2-4
exit
vlan 2
name "camera"
exit
vlan 3
name "pabx"
exit
vlan 4
name "wireless"
exit
hostname "sw_L3"
slot 1/0 3 ! Dell Networking N3048
stack
member 1 4 ! N3048
exit
interface out-of-band
ip address 192.168.254.10 255.255.255.0 192.168.254.1
exit
ip routing
ip helper-address 192.168.1.5
interface vlan 1
ip address 192.168.1.4 255.255.255.0
ip netdirbcast
bandwidth 10000
exit
interface vlan 2
ip address 192.168.2.1 255.255.255.0
bandwidth 10000
exit
interface vlan 3
ip address 192.168.3.1 255.255.255.0
bandwidth 10000
exit
interface vlan 4
ip address 192.168.4.1 255.255.255.0
bandwidth 10000
ip helper-address 192.168.1.5 dhcp
exit
ip route 0.0.0.0 0.0.0.0 192.168.1.2
username "admin" password 51a32d722dd3b81772a68c7449d5e62d privilege 15 encrypte
d
dhcp l2relay
!
interface Gi1/0/1
switchport trunk allowed vlan remove 1-4093
exit
!
interface Gi1/0/39
switchport access vlan 3
exit
!
interface Gi1/0/40
switchport access vlan 3
exit
!
interface Gi1/0/41
switchport access vlan 4
exit
!
interface Gi1/0/42
switchport access vlan 4
exit
!
interface Gi1/0/43
switchport access vlan 2
exit
!
interface Gi1/0/44
switchport access vlan 2
exit
!
interface Gi1/0/45
switchport mode general
switchport general allowed vlan add 2
switchport general allowed vlan remove 1
switchport trunk allowed vlan 1,3-9,11-19,21-4093
exit
!
interface Te1/0/1
switchport mode trunk
switchport trunk allowed vlan 1-4
exit
!
interface Te1/0/2
switchport mode general
switchport general ingress-filtering disable
switchport general allowed vlan add 2-4 tagged
switchport general allowed vlan add 1 tagged
switchport trunk allowed vlan 1-4
exit
snmp-server engineid local 800002a2033417ebfe05f8
snmp-server community "public" rw ipaddress 192.168.254.254
exit

-------------------------------------

!Current Configuration:
!System Description "Dell Networking N2048P, 6.2.0.5, Linux 3.6.5-1289203e"
!System Software Version 6.2.0.5
!
configure
vlan 2-4
exit
vlan 2
name "Camera"
exit
vlan 3
name "PABX"
exit
vlan 4
name "Wireless"
exit
hostname "sw_L2"
slot 2/0 9 ! Dell Networking N2048P
sntp broadcast client enable
clock timezone 4 minutes 0
stack
member 2 9 ! N2048P
exit
ip routing
ip helper-address 192.168.1.5
ip helper-address 192.168.1.55
interface vlan 1
ip address 192.168.1.3 255.255.255.0
exit
interface vlan 2
exit
bandwidth 10000
interface vlan 3
exit
interface vlan 4
ip netdirbcast
bandwidth 10000
exit
username "admin" password d0071ce51fa4c9373336b76bc73e9f59 privilege 15 encrypte
d
dhcp l2relay
dhcp l2relay vlan 4
!
interface Gi2/0/1
switchport access vlan 3
switchport trunk allowed vlan 1-29,31-4093
exit
!
interface Gi2/0/2
switchport access vlan 3
exit
!
interface Gi2/0/3
switchport access vlan 3
exit
!
interface Gi2/0/4
switchport access vlan 3
exit
!
interface Gi2/0/5
switchport access vlan 3
exit
!
interface Gi2/0/6
switchport access vlan 3
exit
!
interface Gi2/0/7
switchport access vlan 3
exit
!
interface Gi2/0/8
switchport access vlan 3
exit
!
interface Gi2/0/9
switchport access vlan 3
exit
!
interface Gi2/0/10
switchport access vlan 3
exit
!
interface Gi2/0/11
switchport access vlan 3
exit
!
interface Gi2/0/12
switchport access vlan 3
exit
!
interface Gi2/0/13
switchport access vlan 3
exit
!
interface Gi2/0/14
switchport access vlan 3
exit
!
interface Gi2/0/15
switchport access vlan 3
exit
!
interface Gi2/0/16
switchport access vlan 3
exit
!
interface Gi2/0/17
switchport access vlan 3
exit
!
interface Gi2/0/18
switchport access vlan 3
exit
!
interface Gi2/0/19
switchport access vlan 3
exit
!
interface Gi2/0/20
switchport access vlan 3
exit
!
interface Gi2/0/21
switchport access vlan 3
exit
!
interface Gi2/0/22
switchport access vlan 3
exit
!
interface Gi2/0/23
switchport access vlan 3
exit
!
interface Gi2/0/24
switchport access vlan 3
exit
!
interface Gi2/0/25
switchport access vlan 3
exit
!
interface Gi2/0/26
switchport access vlan 3
exit
!
interface Gi2/0/27
switchport access vlan 3
exit
!
interface Gi2/0/28
switchport access vlan 3
exit
!
interface Gi2/0/29
switchport access vlan 3
exit
!
interface Gi2/0/30
switchport access vlan 3
exit
!
interface Gi2/0/31
switchport access vlan 4
exit
!
interface Gi2/0/32
switchport general pvid 4
switchport general allowed vlan add 4
switchport general allowed vlan remove 1
switchport access vlan 4
exit
!
interface Gi2/0/33
switchport access vlan 4
exit
!
interface Gi2/0/34
switchport access vlan 4
exit
!
interface Te2/0/1
switchport mode general
switchport general ingress-filtering disable
switchport general allowed vlan add 2-4 tagged
switchport general allowed vlan add 1 tagged
switchport trunk allowed vlan 1-2,4-4093
exit
!
interface Te2/0/2
switchport access vlan 4
exit
snmp-server engineid local 800002a203f48e3806c0a6
exit

I have created an entry on the Sonicwall as follows:

route 192.168.4.0/24 192.168.1.3 (IP address of 3048)

I am able to connect the DHCP server and obtain IP through 4.0 VLAN, however, the internet is not getting connected. Please assist.