You have two internet lines, but one big download still crawls as if only one line existed. This is exactly the problem solved in the video — an office with multiple leased lines where a single download was stuck at 25 Mbps on one line and 10 Mbps on another, until both were combined to finish 50-60 GB transfers faster.
First, the honest truth that every page on this topic should start with: combining two connections does not double the speed of a single download by itself. A normal download is one session, and one session normally travels on one line. There are two real ways to combine lines: load balancing, which spreads many sessions across both lines, and true bonding, which splits and rejoins one stream with help from a server on the internet. Both are useful — for different jobs. This guide walks through the methods end to end, in the same order the video tests them.
Load balancing is what a dual-WAN router does. Every new session — a download, a video call, a web page request — is placed on one of the two lines. Ten users, or one user with ten downloads, feel the full combined power. But one single session still gets only one line's speed.
Bonding is different. A bonding tool splits one stream into pieces, sends them over both lines at the same time, and recombines them at a server on the internet before forwarding them to the destination. Only bonding makes one download faster — and it always needs that outside server, so it is normally a paid service or a VPN you build yourself.
This is the right method when many people or many devices share the two lines:
From now on, new sessions are shared between the lines automatically. Where this genuinely helps: offices with many staff, homes with many devices, and any single user who runs several downloads at once.
If the two lines end at one PC — say one cable from each router — Windows gives you a smaller, more limited version of the same idea:
route print -4 — you will see two default routesnetsh interface ipv4 set interface "Ethernet 2" metric=15Be clear about the limit: Windows does not bond two adapters by itself. Metrics only choose which line is primary. Real per-download gains on one PC come from the router in Method 1, from a multi-connection download manager (Step 5), or from bonding software (Step 4).
When the job is literally one huge file on one PC — the 50-60 GB transfer problem from the video — bonding is the honest answer:
The costs are real too: a subscription, a little added latency, and speeds slightly below the pure sum because of overhead. If your need is occasional, Method 5 below is free and often enough.
Here is the practical trick behind the video's result. A good download manager (Free Download Manager, IDM and similar) does not download a file in one stream — it opens 8, 16 or 32 parallel connections to the server and downloads different pieces at once. Behind a load-balancing router, those parallel connections are spread across both lines, so one big file effectively uses both:
Honest limit: this only works for downloads from servers that allow multiple connections and resume. A single browser download or one video stream cannot be split this way.
A normal speed test opens connections to one test server and may still land mostly on one line, so it can look as if nothing improved. Test like this instead:
If the combined total is close to the sum of the two lines, your setup is working exactly as physics allows. In the video's office, that meant roughly 25 + 10 = 35 Mbps of real transfer speed instead of waiting on one capped line.
The full video shows the real office problem, the combining methods and live speed testing — watch it before you change your own network.
▶️ Watch Full VideoFor your network as a whole, yes — two users or many downloads together can use about 100 Mbps. For one single download, no — not with load balancing alone. That one download stays on one 50 Mbps line unless you use true bonding or a multi-connection download manager behind a load-balancing router.
For load balancing, yes — you need a dual-WAN router (or a router whose LAN port can be converted to a second WAN). A normal single-WAN router cannot share two lines. One PC with two adapters can only prefer one line at a time without extra software.
No. A game uses one connection, and load balancing can even cause a disconnection if your session is moved mid-game. Pin the gaming PC to your most stable single line with a router rule, and let the second line carry downloads and other users.