NE05路由器做外网主路由，无法上网，请各位大哥帮忙解答，谢谢

NE05(config)#show run
Building running configuration...
Current configuration is :
!
hostname NE05
enable password level 15 7 U>!;)@![B>[A74'IP2>CN!!!
enable vlan mode L3
!
!
!
class-map match-all shipinout
match ip dscp ef
class-map match-all shipin
match ip dscp ef
match access-group 101
!
policy-map shipinout
class class-default
class shipinout
bandwidth 2048
policy-map shipin
class class-default
class shipin
!
interface Ethernet4/0/0
!
interface Ethernet4/0/0.1
description goto zongdui
encap dot1q 3077
!
interface Ethernet4/0/0.2
encap dot1q 813
!
interface Ethernet4/1/0
description goto shizhengwang
ip address 172.20.8.253 255.255.255.252
nat server protocol tcp global 172.20.8.253 any inside 192.168.1.0 any
!
interface Ethernet4/2/0
description danwei
ip address 192.168.1.1 255.255.255.0
!
interface NULL0
!
!
!
!
ip route 0.0.0.0 0.0.0.0 172.20.8.225 preference 60
!
line con 0
line aux 0
no login
line vty 0 4
no login
!
end
NE05(config)#
请帮忙看看问题出在哪里？
环境：
外网：172.20.8.253 255.255.255.252 172.20.8.225
内网：192.168.1.1－254
路由器NE05，不知道是不是路由器太老了。DHCP命令没找到，也不知道是哪里出了问题，网络一直搞不通，请各位师傅指点