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How to access LAN hosts which has no (missing) default gateway from Internet?

I have configured a Cisco IR829GW (network diagram attached), so that, I can access remote site (LAN hosts) from my home PC. Cisco IR829GW is a 4G router. My SIM card subscriber providing DHCP IP to the Celllular interface of IR829GW.

Remote site LAN hosts are having two category

(1) host TCP/ IP is properly configured. Meaning IP, netmask and default gateway are configured
(2) host TCP/ IP is not properly configured. Meaning default gateway is not configured.

Hosts from category 1 can access internet and those are also accessible from internet (from home PC).
But host from category 2, neither can access internet nor can be accessed from internet (home pc). These hosts are running UltraVNC (TCP/5900), by default. I would like to access to those PCs remote desktop from my home PC. Is it possible? If yes, could someone kindly advise me.

I have also attached configuration file here.

Thanks you in advance.


network diagram




Without a default gateway

Without a default gateway configured the options I can think of are:

  1. Configure the default gateway
  2. Add a static route to the machines
  3. Access one of the properly configured machines on the same LAN and then use UltraVNC from this machine to access one of the machines without a gateway

If you have the ability to configure the default gateway this is likely the best option.


Hi Brandon, Thanks for your

Hi Brandon, Thanks for your prompt response. It's hard to get access to those remote LC PC because those doesn't have even any display.

I found (by googling) some cheep 3G/4G router is capable of doing this as SNAT

This function transparently passes on the incoming data traffic from Internet or VPN connections
to the LAN. In other words, all data packets going to the LAN are assigned the IP address of the
router as the sender address. This means that none of the LAN subscribers need the router as a
“gateway”. This is a considerable advantage when integrating remote maintenance into existing
network structures as it means that these structures do not need to be changed....


configuration is attached but here is

interface Cellular0
 ip address negotiated
 ip nat outside
 no ip virtual-reassembly in
 encapsulation slip
 dialer in-band
 dialer idle-timeout 0
 dialer string lte
 dialer watch-group 1
 async mode interactive
interface Cellular1
 no ip address
 encapsulation slip
interface wlan-ap0
 no ip address
interface Vlan1
 ip address
 ip nat inside
 ip virtual-reassembly in
interface Async0
 no ip address
 encapsulation scada
interface Async1
 no ip address
 encapsulation scada
ip forward-protocol nd
no ip http server
no ip http secure-server
ip nat inside source static tcp 80 interface Cellular0 8888
ip nat inside source static tcp 5900 interface Cellular0 5900
ip nat inside source static tcp 5900 interface Cellular0 5910
ip nat inside source list 101 interface Cellular0 overload
ip route Cellular0
dialer watch-list 1 ip !-- this is generating bogus trafic to keep the cellular 0 interface up.
dialer-list 1 protocol ip permit
ipv6 ioam timestamp
access-list 101 permit ip any any

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