I have two 4G LTE router modems in my office which we want our clients connect to these modems to have access to the internet.

I have a shared server which should connect to these both modems that each client can access the shared server.

currently we connected this two modems to a ethernet switch which server is also connected to this switch. but the problem is whenever one of this modems credit runs out, our clients will disconnect from the internet temporarily and they have to disconnect and reconnect to gain network access again.

I want to buy a cisco or microtik access points and configure it to be able to achieve this configuration, but thought better to ask from professionals first.

This is my current network digram : network configuration

please give me digram of proper configuration and protocol.

1 Answer 1


The problem is that your public IP address changes when you switch routers because each router has a different public address, and your server is running on a private address. You need your server to have a public address so that connections from the outside connect to the server, not the NAT on a router.

It is becoming more difficult and expensive to acquire public IPv4 addresses every day that passes since the RIRs ran out of them. If both connections are from the same ISP, then you can probably negotiate a deal with it, otherwise you will need to buy provider-independent IPv4 addresses on the open market, which will require you to exchange BGP prefixes with your ISPs. This will necessitate you getting proper business-grade routers that can run BGP. (The consumer-grade devices you currently have are off-topic here.)

  • The point here is that i want clients in our office be able to connect to this server and not outsiders. meaning i want local network. but current configuration is not that much helping. some of the clients are kicking from network suddenly and as i said before whenever on of my modem disconnect from net, users should reconnect to the network. Jan 9, 2018 at 6:34
  • I explained to problem. When someone is connected to the IP address of a router instead of the server, when that router goes down, the server address, in essence, is changed to the other router's IP address. You need to connect to the server's address. Connection-oriented protocols, like TCP, require that the addresses on a connection not change, and if they do, the connection is lost. You would need a public address on you server. You can use a firewall, or other method, to allow or deny access, but your problem is that the address changes when a router goes down.
    – Ron Maupin
    Jan 9, 2018 at 6:39
  • @Mohammad_Hosseini, let me put it this way. I have two phone lines. Suppose you call me on line 1, and we are having a conversation. Then the service to line 1 is cut, why would you expect your connection to me to automatically switch to line 2?
    – Ron Maupin
    Jan 9, 2018 at 6:41
  • @Ron_Maupin I get it. but problem is not the server because i defined it it iptables and set a static ip for it by mac filtering. problem is dissconnecting from internet. let put it this way, suppose i need this kind of configuration which i want every client can connect to the internet from both modems and also can connect to the file server also, what should i do ? Jan 9, 2018 at 7:13
  • I explained that. You need a block of public IP addresses. The IP paradigm is that every device has a unique IP address. NAT breaks that, but it was necessary because we are out of IPv4 addresses, and it is a stopgap until IPv6 is ubiquitous. Connections simply cannot tolerate changing the IP address, and people outside your office, while it looks like they are connecting to the server, are really using the IP address of one of the routers, and when that IP address goes away, so does the connection. IPv6 restores the IP end-to-end paradigm.
    – Ron Maupin
    Jan 9, 2018 at 7:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.