Can Windows 10 on A modern laptop support simultaneous connections to two ISPs?

Solution 1:

This is possible even though Windows doesn't deal well with this on its own.
(At least in this particular use-case, where there is a limited number of connections that need the low-latency DSL connection, it is do-able.)

1. Configure the satellite router as the normal default router to for the local LAN.
   Have it provide DHCP and DNS to the local LAN as usual.
2. On the DSL router disable it's DHCP service and give it a static IP-address in the LAN ip-range that doesn't conflict with the DHCP pool from the satellite router.
3. For each service/server that you want to run through the DSL connection:
   Determine the ip-address (or ip-range) for that service/server.
   On the Windows 10 PC create a static route (using the route add command, don't forget to ad a -p to make the route persistent across reboots) that sets the gateway for that ip-address (or range) to the LAN IP-address of the DSL router.

This setup will use the satellite link for all internet traffic, except for those connections, that have a route that directs that connection to the DSL. Unless you make an explicit route to point to the DSL router it will otherwise be as if the DSL router doesn't exist. It won't interfere with anything else, so local printers, NAS, etc. will keep working as usual.

Nice thing about this is that this will work via a single network interface on the Windows 10 computer. You can still use wired or Wifi as required.
And if you have multiple computers you can apply the routing to each individually as needed.
It is also OS agnostic. It will work with any OS that allows you to manually add static routes.

Only drawback is that if you wan't to use the computer on another network, you will have to remove those static routes temporarily in order to be able to use those servers/services normally while you are on the other LAN.

Solution 2:

This is possible. I know of one program that can do this: ForceBindIP. It requires you to run each program from the command line and tell it which IP or GUID to use, if other than the default.

Solution 3:

I would opt for a multi-WAN router instead.

I've seen that these offer load-balancing support, but I'm not sure if that is customizable to send certain traffic across one network versus the other; you'll have to read into the router's documentation before buying one.

This one seems to allow you to alternate WANs based on port number being used. US$179 isn't terribly expensive given the functionality.

I suggest this because even if you succeed in getting Windows 10 to do smart network switching then you'll have to repeat the process if you desire another machine to behave similarly. Also, such changes could present huge headaches if you have to use someone else's network or if your router breaks and you get a new one.

The multi-WAN router would be much more robust and reliable solution.

Getting a purpose-built networking device to achieve your goals is going to be far easier than coercing a user-oriented operating system to do something unnatural.

The other option for your "interactive" work (RDP right?) is to just get an el cheapo laptop connected to the DSL which can handle your desired monitor resolution and alternate machines as needed.

Solution 4:

Just to add to MonkeyZeus's answer.

Given the speed the internet access in your area you might be able to save a few bucks by eBay'ing a SOHO (small office home office) commercial firewall. Specifically you only need 10/100 not gigabit for internet access, so those old units are virtually worthless for corporate use, hence they usually eBay for around $20.

The setup I am envisioning is:

          +---------+
        /-| Printer |
        | +---------+
+-----+-/             +---------+ 
| SAT |---------------| Storage |
+-----+--             +---------+
        |    
        \----+----------+         +---------
             | Firewall |---------| Laptop | 
        /----+----------+         +---------
+-----+ |   
| DSL |-/
+-----+

You should continue to keep the laptop on the WIFI for the Satellite. You will need to move both the printer and the storage onto that network (reason below).

The firewalls WAN ports are each connected to the two routers. And the internal connection of the firewall is connected to the laptop. This will result in a "Double-Nat" situation. That shouldn't be a problem for internet access, but it will be a problem for the printer and the storage - which is why I said to keep the Wifi connected and move both of them onto that network.

The critical points here are:

The firewall can be configured to send traffic to the relevant route based on port used:

• http/https -> satellite
• RDP -> DSL

The laptop should use the wired connection as its default route as soon as its plugged in (no configuration necessary).

However since the wired connection is on a different IP range the laptop should still use the WIFI to access local services such as the printer and storage.

Back in the day I used to use old Sonicwalls for this, typically either a TZ-170 or TZ-205 - however its been over 7 years since I used them so please don't put to much weight into a particular brand.

A few final thoughts:

This setup is a little complicated, I am only really recommending it to save a few bucks - if you have the money just buy a dual wan router per MonkeyZeus's recommendation.

I have taken setups like this even further by running a VPN over each link. That allowed me to do asynchronous routing and traffic shaping. However it required a cloud server to terminate both VPN links and shape the downstream traffic - so unless you really want a "hobby project" thats probably outside the scope of what you are trying to achieve.

The nice thing about this setup is it doesn't require you to change anything on either your existing routers or the laptop. Just plug in the new firewall - if you can't get it working you just unplug it - you will be out $20 but you will be immediately back to where you were - you can't screw anything up.