Originally I had an Intel AC 3165 wireless card in my notebook, but I couldn't use simple wireless internet connection and miracast together, one of them was always unusable, so I bought an AC 8265 card. I've successfully installed it into my notebook, I installed the newest drivers, etc... Now everything is a little bit better, I have no lagging issues on screen mirroring, but when I turn on miracast (so when I connect to my TV), the internet speed immediately drops down, my download speed from 3.6MB/s drops down to 20-40KB/s. A simple website is loading for minutes, youtube starts loading videos with 144p (and can't play them either)... This is horrible. I was searching about the problem, and I've found some solutions that helped others: I disabled the "Receive Segment Coalescing State", but didn't helped. I was continue searching, I had run the following commands too:
netsh int tcp set heuristics disabled
netsh int tcp set global autotuninglevel=disabled
netsh int tcp set global rss=enabled
Checked, all values has been changed successfully. I've restarted my computer.
Nothing changed, the problem is still present.
Okay, I continued searching... In an other topic, the problem was the wifi encryption, but I checked, I'm having WPA2-PSK with AES encryption too... The router firmware is also the newest. (TP-Link TL-WR841ND V7, channel 13 (not the same channel as miracast), mode is 11n only for always the fastest speed)
By the way, I'm connecting to a Microsoft Wireless Display Adapter (v2) and I have Windows 10 Creators Update. I started using miracast on this version, so I don't know, if there is any differences with other versions.
I created two reports using SSU, one with Miracast OFF and one with Miracast ON.
I hope, we can find any solutions (that not needs reinstalling the OS).
We understand you have been experiencing slow download speeds while Miracast* is enabled on your Intel® Dual Band Wireless-AC 8265 adapter.
It's important to point out that we do not provide support for custom wireless integrations (upgrades). And while the 8265 is compatible with Miracast*, the support for this technology is provided by Microsoft*, as it is a native feature of the operating system. Alternatively, you may rely on your http://www.intel.com/content/www/us/en/support/topics/OEMs.html computer manufacturer for assistance if they were the ones who installed the new wireless adapter on your PC.
- http://www.intel.com/content/www/us/en/support/network-and-i-o/wireless-networking/000005687.html Regulatory Information Regarding Wireless Hardware Installation or Upgrade.
We have reviewed both System Support Utility reports, and from our end everything looks optimal. On both reports we can see a connection speed of 300 Mbps, which is the top speed your router is capable of. Our only recommendation could be to set your adapter to HT Mode, which will disable Wireless-AC and increase compatibility with legacy 802.11n networks.
- Device Manager > Network Adapters > Intel(R) Dual Band Wireless-AC 8265 > Double click to access Properties > Advanced Tab > HT Mode = HT Mode (VHT Mode = 802.11ac).
One thing to know about the Microsoft Wireless Display Adapter. It uses its own WiFi network, so it's not connected to my router or anything. I don't know, if all Miracast connection is the same, or the most common method is working through my router's WiFi. Is it possible, that the problem is this? So for example, if I buy a smart tv that supports Miracast and connects through my router, can the connection turn better? Or this kind of Miracast connection doesn't exists, so nothing would change?
It's also likely that your issue is being caused due to the differences in antenna configuration from your old adapter.
The Intel® Dual Band Wireless-AC 3165 uses a 1x1 antenna configuration. This type of adapters use one antenna for wireless (send and receive), and a second that is only for Bluetooth*.
Meanwhile your new Intel® Dual Band Wireless-AC is a 2x2 adapter. Meaning it has two antennas that are used to send and receive wireless packets, the second antenna is shared between Bluetooth* and wireless.
When you enable your wireless display sharing, this adapter will then use one antenna for wireless, and one for wireless display. Since your second antenna was originally intended only for Bluetooth* it may be a smaller gain antenna since Bluetooth* devices will normally be closer to your PC. So when your 8265 starts sharing your display, the antennas may not be able to provide the required bandwidth, resulting in your slow connection.
I bought a Sony TV yesterday, it supports Miracast. There is no problem with the internet any more... I don't know, what's the difference between the Miracast in the two devices (Microsoft Wireless Display Adapter and Sony TV), but it's working now, my internet is on full speed.
Thanks for all the help.