I am struggling since a while with a strange phenomena; when MSFS2020 runs then speedtest shows dramatically slower network speed on MSFS PC. I would not care too much, but other day even Vpilot client disconnected, web browser could not load pages. I can only observ this strange behaviour with MSFS, in fact I have no other gane to test.
ISP: 2.5Gbps fiber optic, provided Zyxel router
Home Network: Zyxel router → LAN cable → 1Gbps switch → direct LAN cable to RJ45 sockets (3x), direct connection to NAS
My Windows 11 PC (MSFS) connected to RJ45 in office area shows extremely fluctuating internet speeds, therefore made the following measurements. My expectation would be to measure app.1000Mbps up/down on each connection point after router.
How is it possible, when MSFS2020 is running the download speed drops from 941Mbps to 170Mbps? It is consistent with repeated measurements
Why speedtest.net desktop app measures slower speed than web? Refer to measurement on 01.05, but same observation made every time web and desktop app compared
As I can see from ISP side everything seems OK, as my Macbook everywhere can achieve the desired speed, looks like somehow only Win11 interferes with network speed very strangely.
QoS is disabled on router. Any hint, advice? I am stuck here.
You let run msfs, which cause a lot of online-traffic because it needs a lot of data, and then you run in parallel a speedtest ???
And you use the word “slow” with Upload-Rate greater than 150Mbit ?
Some guesses about your points:
1 - network drivers
2 - because MSFS use the bandwith
3 - speedtest.net is not a reference environments
What we also can see: you have 2.5fiber , but only a switch/router which supports 1Gig. For some people in the world, would simple 1Gig be like a dream comes true.
You have a location named office and then on one of the Mac tests you mention Zyxel router lan port as the location.
That implies to me that the Office location might be a wi-fi connection? If that’s the case then the wi-fi adapter or it’s drivers on Windows 11 may be the culprit.
If I’m correct in my guess there, is it possible to plug your Windows 11 machine into the Lan port of your router?
The other oddity as MichaMMA pointed out is why have they provided you only a 1Gbit switch with a 2.5Gbit connection?
Edit : sorry just realised you said it was already connected by RJ45
Still seems a bit odd that they provided you with a router that isn’t capabale of running at the speed you are paying for.
As I wrote, I would not mind the slow(er) speed, but there been times when it went below 5Mbps speed and Vpilot disconnected due to time-out.
Everything is relative…sorry, if I am posting about my technical problems and not about others. Yes, if it shall be 1000 and below 100 that is an issue and would like to know why.
The router is capable, because in parallel on two of it’s 1Gb LAN port I can measure in the same time 1Gb up/down speed, which is basically 2Gb…my real concern is the Win11 (MSFS) PC and how it internet speed drops when MSFS is running…I hardly believe MSFS blocks 600Mbps download speed
do you own a managed switch ? at least one where you can check traffic ?
You can check the taskmanager what’s going on with your network traffic while msfs is running. Did you checked this already ?
Its just hard to say without the knowing whether realy the win11 pc network is in full usage.
Otherwise it can be lot of things,… starting from network drivers, hardware like mentioned cables, or the switch, or… May possible is also a limit which is set in windows, or a antivirus-firewall-add-on.
Well I’m running on Windows 11 with a 300Mbit Download/30 Mbit upload connection and it works OK. If I do the speedtest without MSFS running I get the full 300 with MSFS running it still gives me 250 plus depending on how much MSFS is using at the time.
Maybe the drivers for your Windows 11 network adapter are not very good? My PC has two Ethernet ports. One is a Killer networks connection and the other is Realtek. The killer one doesn’t work well as I can’t find drivers for Windows 11 (it’s on the old Windows 10 driver) and I get slow speeds on that connection. If I use the realtek one it’s fine.
Your results are fully reasonable, I would expect similar differences, but as in my last post shown, I have 10x slower download speed when MSFS runs.
It is a HP Omen gaming PC, purchased last year especially for MSFS…it has a realtek onboard network port, and HP tool says it is up to date and also could not find any other driver.
I have also tested using a LAN adapter plugged in into onboard USB-C, but same experience.
I don’t think that is right at all. MSFS uses very little download as it runs and even then it is in bursts. I can tell no difference on my connection 400 Mbps.
Try streaming a 4K video from youtube as you test w/o FS running.
Maybe your ISP throttles certain types of traffic and it sees FS as a type it throttles.
700 subtract that 3.2 shouldn’t cause the degradation that you are seeing. Can you plug your modem directly into the PC? Disable and then re-enable your network connection so it pulls a new IP and then test again?
Unfortunately the ISP router is far from the desktop, so I can’t connect directly.
What I can do (and did in the past) on the router release the IP and renew or just reset, but I have tried this already.
Btw. 4K video streaming is OK now, even with MSFS, but there are times when speed slows down so much even a google.com is not loading. When closing MSFS, everything goes back to “normal”.
Wait,
You don’t happen to have your data speed capped in MSFS do you? I did it once for testing and forgot it, then when the next SU came out, it took an entire day to DL. Check that.
Check, speed is not capped in MSFS (BANDWITH - UNLIMITED), ), but even if it would, then that shall not impact speedtest.com in browser.
Below is a measurement when MSFS+4K streaming was running: 120Mbps/170Mbps down/up. The yellow marked is the 4K streaming (looks strange, but I am not an expert). Red marking where the speedtest.net was testing
There are many different factors impacting network speeds. Raw network speed is only one indicator of performance. For example, your network might have a lot of packet retransmissions due to various errors. It is impossible to tell just from speed tests.
Windows 10 has various “troubleshooters” built in. Windows 11 should have something similar. Windows might find something wrong with your network configuration and fix it.
If Windows doesn’t find anything, check Windows and your router logs for errors especially firewall errors. Routers can change network parameters dynamically possibly negating Windows settings. It may see MSFS traffic as a huge download so it throttles MSFS traffic so that other users on your network aren’t impacted.
If you are still having network problems then the next step is to capture a network trace while MSFS is running. This will provide massive amounts of detail about your network traffic. If you are familiar with TCP/IP, you could analyze the trace for potential issues. Otherwise a network professional would have to analyze the trace for you. Depending on what the trace captures, it is possible to determine any problems with MSFS traffic as well as the actual round-trip network latency between your computer and the MSFS servers. A network trace doesn’t fix anything. It is very helpful in finding any issues. BTW MSFS traffic is encrypted so there is no information about the contents of the traffic.
