How to cast a laptop screen to the TV? Win+P couldn't find the TV and was stuttering—I managed all four options one by one

daughter-in-law's company-issued thin laptop had a 13-inch screen. On weekends, she wanted to watch her child while finishing the quarterly spreadsheets, squinting for half an hour before rubbing her neck. The 4K TV in the living room was idle, so I said I could use it as a monitor—the screen was four times larger, and the table could be seen in three columns at a glance.

actually realized, computer screen casting and phone screen casting are completely different things. I once wrote an article about the phone setup for checking TVs when casting from your phone, and most failures are stuck at the 'TV not found' step. The computer side has more options, but the pitfalls are even trickier: wired has its own tricks, wireless has its own temperament, and there's the copyright black screen pitfall waiting for people. I went from stable to unstable on four routes, giving a thorough answer to each one.

first understand Win+P: Computers have a level of gameplay more than phones

any Windows computer, press the Win and P keys on the keyboard simultaneously. Four options pop up on the right side of the screen: Computer Screen Only, Copy, Expand, and Second Screen Only. These four levels are all the positions for computer screen casting. First, distinguish them clearly before you start.

"Copy" means two screens display the same image, showing photos to parents or submitting materials in video conferences—use this. "Extension" is the computer's unique feature—the TV becomes a second screen, the mouse swipes to the edge of the screen, the table drags onto the TV, and the home screen stays working. Phones don't have this concept; phone screen casting can only be copied.

so before you start, think carefully about which one you want: watch videos and choose copying; for work, choose extensions. To extend it, set the → system → display and drag the thumbnails of both screens to actual opposite positions with the mouse—the TV is placed to the right of the laptop, and swiping right makes it smoother. If the default position is wrong, the mouse swipes for a long time without finding direction. On my first attempt, I swiped at the air for half a minute.

First Way: Direct HDMI Cable Connection, the Most Rustic but the Most Stable

find any HDMI port on the back of the TV, plug the laptop close, and switch the signal source to the corresponding HDMI channel. That's it. Zero latency, zero settings, no need for WiFi—among the four options, this is the only guaranteed lag-free solution. My advice has always been: use wireless for the time being, and do serious work by pulling the cable.

but the thread has its own considerations. The first cable I found was the HDMI cable that came with the set-top box from ten years ago. When plugged into a 4K TV, the system only gave a refresh rate of 3840x2160@30Hz—this cable is HDMI 1.4, with a bandwidth of 10.2Gbps. Running 4K at just 30 frames per second, the mouse swipes over it with a bit of a pause, making dynamic footage especially uncomfortable. I switched to a 2.0 cable (18Gbps) printed on the packaging, and it immediately recognized it as 4K@60Hz, smooth. Buy online, choose "HDMI." 2.0" or "4K@60Hz" marking, and you can't tell the difference between a tiny or thirty yuan one—don't pay extra for the brand.

another pitfall at the interface. Nowadays, ultrabooks are popular to have HDMI ports removed, leaving only Type-C on the body. The adapter costs a little over ten yuan, but you must make sure to use the fully functional USB-C port that supports video output—plugging in the charging port has no response, so I wasted all the effort using the cable my wife came with with the charger. Her unit had a Thunderbolt port, so later I just used a docking station, solving the problem with both the network port and USB.

after connecting, don't rush to use it. Go to the display settings and set the zoom to 125% or 150%. A 4K screen defaults to 100% rendering, and the text on the TV is as tiny as ants—you can't watch it from three meters away.

second way: Win+P connecting to wireless monitors, convenient but a bit of a

don't want to pull cables, just go wireless. The TV first turns on the receiver switch—domestic TVs are usually called "wireless display" or "screen mirroring," or are hidden within "multi-screen interaction"; On the computer, Win+P selects "Connect to wireless monitor," then on the right side displays the name of the TV. Click it, and the TV will pop a confirmation button, and it connects. The underlying platform uses Miracast, which uses the same protocol as the phone's screen mirroring. The two devices connect point-to-point directly, without taking up router bandwidth, so even if your home WiFi lags, it won't be affected.

"Not finding the TV" is the most common failure point on this road. I rank three reasons based on probability. First, the TV's receiver switch isn't turned on, or the entrance is hidden deep. My unit is hidden in the settings → network and connection → multi-screen interaction, and I had to flip through two menus before I saw it. Second, the computer's wireless network card driver is too old—press Win+R dxdiagand press Enter, click Save All Information, open the text and search for "Miracast"; only if it shows "Available, with HDCP" is the hardware passed; If it doesn't support it, go to the official laptop website and manually install the latest wireless card driver. Don't use the Windows auto-update version, as the version is often delayed by more than half a year. Third, if the firewall or system service blocks the discovery protocol, temporarily close the firewall and search again. If you can find it, that's their job.

after connecting, expect the experience. My living room is about three meters away. Dragging the window lets you feel a delay of a fraction of a second, and the typing echo is noticeably slow. Reading documents and playing slides is fine, but playing action games is out of the question. It's okay for local videos, smooth at 1080P, and occasional frame drops from 4K sources.

there's another particularly frustrating pitfall to mention: opening copyright sites like Netflix in a browser, posting it results in a black screen but still sound. This isn't a lag; it's HDCP copyright protection causing trouble—mirroring doesn't meet the studio's end-to-end encryption requirements, so they deliberately prevent you from investing. The only solution is to bypass it: either plug in an HDMI cable or install the official app on the TV and log in. Competing with wireless won't help.

Third Path: If you only want to show movies, don't use mirrors, go DLNA

if you're not projecting the entire screen but just want to put movies from your computer's hard drive onto the TV, then mirroring is like using a sledgehammer—the computer screen must stay lit constantly, and even a touch of the mouse makes the TV shake. The correct approach is to use DLNA streaming: the computer as the source server, the TV as the player, each doing their own thing.

operation is ridiculously simple: right-click on the video file, select 'Play to Device', select the TV's name, and the TV starts playing. Windows Media Player and VLC both have this feature. Once it's up, the computer does whatever it needs—files downloaded and web pages are browsed as usual, without any interference.

those with NAS at home should recognize this. This is the same logic as NAS for playing movies on TV. NAS the direct connection to the TV, I wrote a full . The difference in computer streaming is that the bandwidth is based on WiFi: my TV uses a 100Mbps network port, while my computer connects to a 5G router. In actual tests, running 1080P MKV is no problem, and a movie with over ten GB bandwidth only has a bit rate of about 20 Mbps, which is no big deal for WiFi. Occasionally, the format goes wrong: DTS tracks can't be unloaded on TV, and the picture has no sound. This is exactly the same problem as the direct NAS playback on the TV.

Fourth Way: Third-party casting apps, keep them as a backup

really have no choice—old TVs don't support Miracast, computer network card drivers are irreversible—third-party casting apps like LeBo or AoRuan have an app installed on the TV and corresponding clients on the computer, and then they get to know each other. The advantage is that compatibility is truly good—even old TVs from ten years ago can be revitalized; The trade-off is that the free version often has watermarks or time limits; if you want to remove them, you have to buy a membership, which costs dozens of yuan per year.

my view is that this thing should be used as a backup. If you really need long-term screen casting, a 3-meter HDMI cable costs just over ten yuan at once, which is much more cost-effective than paying membership fees every year. There's always an HDMI cable lying in the drawer of my TV cabinet. Whoever works at home plugs it in, and combined with the network port reserved on the TV wall during renovation, it's more worry-free than any wireless solution.

laggy, black screen, no sound: one meter matches the number of seats

which four options to choose? In short: do serious work with HDMI cables, use wireless monitors for temporary meetings, use DLNA streaming for movies, and if the first three fail, then invite third-party apps. My current setup is a regular HDMI cable in the drawer, plus DLNA for playing videos, and saving the wireless set for guests to demonstrate for freshness.