Redirect all the traffic from router to proxy server

Question

I don't know if the question is related to the topics on stackoverflow so, if not sorry in advance.

I have the following problem that I'm trying to solve :
I am connected to my university network that requires me to configure my browser to use a proxy. I want to set up a router in my house ( D-Link Dir-300 with Firmware: DD-WRT v24-sp2) and because I am using multiple Android devices that are not rooted ( I can't use global proxy apps ) I was thinking about the following solution :
Question Can I make my router redirect all the traffic from my wireless network to the proxy server that I'm using ( allowing the devices not to configure a proxy server) ?

I have a HTTP redirect tool available on the router configuration page

I looked up the destination IP address from the proxy URL that I was using and I get 4 IP addresses for that node, I tried to use two of them with the source network set to 192.168.1.0 but it didn't work -my browser on the android devices doesn't work without setting up the proxy.

____________________________________ EDIT ____________________________
After looking some more I found this link

#!/bin/sh
PROXY_IP=[IP]
PROXY_PORT=[PORT]
LAN_IP=`nvram get lan_ipaddr`
LAN_NET=$LAN_IP/`nvram get lan_netmask`

iptables -t nat -A PREROUTING -i br0 -s $LAN_NET -d ! $LAN_IP -p tcp --dport 80 -j DNAT --to $PROXY_IP:$PROXY_PORT
iptables -t nat -A POSTROUTING -o br0 -s $PROXY_IP -p tcp -d $LAN_NET -j SNAT --to $PROXY_IP
iptables -A FORWARD -i vlan1 -o br0 -s $LAN_NET -d $PROXY_IP -p tcp --dport $PROXY_PORT -j ACCEPT

How can I modify it to redirect all the traffic udp/tcp etc coming from all the ports?

Solution

Easy option is to configure your proxy on your android device. When setting up the wireless connection select advanced options and enter your proxy settings, on older android devices it's somewhat hidden but I managed to do it on a 2.3 one. For iOS you can add it later to your wifi settings.

If you router is not the main entry point for internet (if it's secondary) you can configure it to route to your PC/laptop. Configure a static IP op your PC/laptop, share internet over there, and configure that IP as gateway on your router. You can install a proxy tool (charles proxy for example) on your PC and configure it to forward your traffic to the internet-proxy. On your devices you still need to setup the proxy, but this time it's your PC's proxy (gateway+8080).