So that's 24 Mbps because it's giving you bytes with the capital B
If you are able to get something around this speed or better with the plug devices I suggest sticking with them, your effort to make a better wifi link is likely to cost more, take up more time, and perform similarly.
At the moment I do not understand why I get 3.10 MiB/s only, the last time it has been about 8. Maybe the difference is because now it is day and the 8 MiB were in the evening / night. So the problem are the neighbours 5Ghz could be an option. I know, I have to test.
Wifi will suffer from radio interference from neighbors, powerline will be much more constant.
What is the speed requirement? For streaming it's more important to avoid dropped packets and high latency than it is to have high speed. Provided you are getting better than whatever the encoding bandwidth is. So here in US on Sling we get 5Mbps TV streams. On some other services like ATT IPTV services I think it's 8 or 12. If you are getting 24 Mbps that is plenty for streaming. On the other hand if you are regularly copying files it could be annoying to wait tens of minutes. But perhaps the solution is a network filesystem so you essentially stream off that.
How can I test with iperf?
PC:
iperf3 -v
iperf 3.1.3
Linux pc 4.15.0-36-generic #39-Ubuntu SMP Mon Sep 24 16:19:09 UTC 2018 x86_64
DVB-Box:
iperf3 -v
iperf 3.2 (cJSON 1.5.2)
Linux ax51 4.10.12 #1 SMP Mon Sep 3 05:18:55 CEST 2018 armv7l
Test AVM Fritz! Powerline 1220E
time lftp -e "mirror -R extr /hdd/test/ -e; exit" -u root, 192.168.178.117
Neu: 1 Datei, 0 Verknüpfungen
1091783290 Bytes übertragen in 300 Sekunden (3.47 MiB/s)
real 5m0,619s
user 0m0,558s
sys 0m1,258s
I noticed, that it paused from time to time. I used a Cat7-cable. The last time I got with this cable 5.29 MiB/s
So I changed to a CAT5-cable and got:
time lftp -e "mirror -R extr /hdd/test/ -e; exit" -u root, 192.168.178.117
Neu: 1 Datei, 0 Verknüpfungen
1091783290 Bytes übertragen in 198 Sekunden (5.26 MiB/s)
real 3m18,424s
user 0m0,580s
sys 0m1,320s
Then I turned 1 plug (near the pc) and got with the CAT5-cable and a phase change:
time lftp -e "mirror -R extr /hdd/test/ -e; exit" -u root, 192.168.178.117
Neu: 1 Datei, 0 Verknüpfungen
1091783290 Bytes übertragen in 276 Sekunden (3.78 MiB/s)
real 4m35,948s
user 0m0,784s
sys 0m1,357s
This is the speed of the HD in dvb-box:
hdparm -tT /dev/sda
/dev/sda:
Timing buffer-cache reads: 624 MB in 0.51 seconds = 1251713 kB/s
Timing buffered disk reads: 345 MB in 3.00 seconds = 117535 kB/s
The result is very bad always with plugs. I hope I can get better results with beamforming and 5GHz-Wifi.
I do streams from my local dlna-server. Mediainfo mentions eg 6 597 kb/s for a movie which cannot be played via WIfi.
That's 6.6 Mbps or less than 1 megabyte per second, so all of your plug results are faster than that. If you can't do it by wifi it's probably because your wifi latency and dropped packets etc are too high. Your powerline result with the cat5 cable is 40 Mbps just like I said. Seriously, set it up and try your powerline stuff, raw speed is not always the main thing
Also note that powerline equipment I think tunes itself over time to reliable modulation type. Check again after an hour of continuous connection.
Set up the powerline gear and then try to use the video box for its intended purpose. Do you actually experience problems?
My experience with WDS is that you will experience problems. Specifically it will just randomly drop out and stay out until you reboot the router. I have no idea why. I just stopped using it.
When it comes to network equipment other than cat5e or better if it gives 25Mbps in real world tests, you're unlikely to get a lot better by any method other than running an ethernet cable.
Can wifi give real-world speeds of 150 or 300 Mbps or better to a single device? Yes, sure, if that device has multiple antennas and isn't too far from the AP and it's operating on 5Ghz and you're not in a crowded apartment building, and .... Under those conditions, some people will even get 600Mbps+ but they're almost always at a distance where they could just run a wire anyway (ie. a laptop 5 meters from the AP). So it's convenience, but not a good measure of real-world across-your-house with tiled bathroom walls between type stuff.
If you need consistently over 100Mbps for your purposes, and you don't get it from stock WiFi, run a wire, it will save you a lot of money and hassle and time, because after trying a crapload of other stuff, you will eventually run that wire 
On one side
iperf3 -s -fmon the other side
iperf3 -c <ip of the other side> -fmWith the AVM plugs:
isn't this similar to the 5MiB/s with lftp?
~# iperf3 -c 192.168.178.100 -fm
Connecting to host 192.168.178.100, port 5201
[ 5] local 192.168.178.117 port 41364 connected to 192.168.178.100 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 4.51 MBytes 37.8 Mbits/sec 0 191 KBytes
[ 5] 1.00-2.00 sec 4.35 MBytes 36.5 Mbits/sec 0 191 KBytes
[ 5] 2.00-3.00 sec 4.35 MBytes 36.5 Mbits/sec 0 191 KBytes
[ 5] 3.00-4.00 sec 4.27 MBytes 35.8 Mbits/sec 0 191 KBytes
[ 5] 4.00-5.00 sec 4.41 MBytes 37.0 Mbits/sec 0 191 KBytes
[ 5] 5.00-6.00 sec 4.22 MBytes 35.4 Mbits/sec 0 191 KBytes
[ 5] 6.00-7.00 sec 4.33 MBytes 36.3 Mbits/sec 0 191 KBytes
[ 5] 7.00-8.00 sec 4.27 MBytes 35.8 Mbits/sec 0 191 KBytes
[ 5] 8.00-9.00 sec 4.33 MBytes 36.4 Mbits/sec 0 191 KBytes
[ 5] 9.00-10.00 sec 4.25 MBytes 35.7 Mbits/sec 0 191 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 43.3 MBytes 36.3 Mbits/sec 0 sender
[ 5] 0.00-10.00 sec 43.2 MBytes 36.2 Mbits/sec receiver
iperf Done.
Yep, that confirms, around 35 Mbps. This is about 5 times what you need to watch your 6Mbps video. It's almost twice the bandwidth required to carry a full high definition digital television signal broadcast here in the US on the ATSC standard. It's about the typical bandwidth required to transmit a BluRay stream.
So, again, what are you trying to achieve that this doesn't already solve? You have the powerline equipment in-hand. It's almost certainly considerably cheaper than buying some dual-band routers. It probably is going to work as well or better than your dual-band router setup that you eventually get set up. It will certainly take you tens of hours to set up the dual-band router solution. The dual-band router solution will be subject to neighbor interference. The speed you can expect from a dual band router set up is probably at most about twice what this offers...
Unless something you want to do doesn't work with this plug set up... sticking to the plug setup is the cheapest, lowest time investment, most reliable way to solve your problem.
EDIT: and by the way if you want a second wifi AP near your video device to improve your wifi signal, you can certainly put it on the other end of this plug setup and provide a better signal in that area.
In theory you are right. Today I wached Internet TV with the AVM plugs, no big resolution, more sd than hd and I had so many dropouts, incredible. Never had such a bad performance via wifi,
I did now a test with my current 2,4GHz wifi:
iperf3 -c 192.168.178.100 -fm
Connecting to host 192.168.178.100, port 5201
[ 5] local 192.168.178.117 port 60882 connected to 192.168.178.100 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 11.4 MBytes 95.7 Mbits/sec 0 148 KBytes
[ 5] 1.00-2.00 sec 11.9 MBytes 99.7 Mbits/sec 0 148 KBytes
[ 5] 2.00-3.00 sec 11.9 MBytes 100 Mbits/sec 0 148 KBytes
[ 5] 3.00-4.00 sec 10.6 MBytes 88.7 Mbits/sec 0 148 KBytes
[ 5] 4.00-5.00 sec 11.6 MBytes 97.4 Mbits/sec 0 148 KBytes
[ 5] 5.00-6.00 sec 11.5 MBytes 96.2 Mbits/sec 0 148 KBytes
[ 5] 6.00-7.00 sec 11.8 MBytes 98.6 Mbits/sec 0 148 KBytes
[ 5] 7.00-8.00 sec 11.5 MBytes 96.2 Mbits/sec 0 148 KBytes
[ 5] 8.00-9.00 sec 11.5 MBytes 96.8 Mbits/sec 0 148 KBytes
[ 5] 9.00-10.00 sec 11.5 MBytes 96.2 Mbits/sec 0 148 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 115 MBytes 96.6 Mbits/sec 0 sender
[ 5] 0.00-10.00 sec 115 MBytes 96.5 Mbits/sec receiver
iperf Done.
Wow, now in the evening it is so much better than in the afternoon. My feeling says I must try the 5GHz-band, although I wonder why other networks influence my wifi so much. This is a family house and neighbours are 100-300ft away. The old house is built of big stones from a mountain (not concrete) and bricks and I have problems with the signal within the house.
I noticed in the afternoon with the AVM plugs, that the transfer stopped for a while and that was the reason why I changed the cable. It looks like I had the same problem with the 2nd cable too, when I watched internet tv.
So I fear I have to find a wifi solution.
What I need in any case, is a device, which allows me to use a tv and dvb-box with wifi. TV and dvb-box have ethernet only. And the question then is, fi this device shouldn't be capable to do more.
I have an AVM Fritzbox, which is connected to the internet and from this Fritzbox 3 ethernet Cat6-cables are going to the cellar, the ground floor and the 1st floor. The tv, which should use the wifi-bridge is in the 1st floor. A router is a floor below of the tv (same room location), so I think I can save a router in the 1st floor and use the rooter below for the tv. And then we are again at this discussion. I need something to make the tv, a.so. wifi capable and connect to the router below. As already discussed for this situation I do not need wds, but it would be nice to have 1 ssid for about 10 mobile phones. At the moment I have 2-3 SSID which have to be changed at the mobile phones from time to time. In theory this should work automatically with an app, but it doesn't. The 10 phones can be registered at the same time, but are not used at the same time. Normally max 3 phones are used at the same time. Same with TVs. There are 4 TVs, 3dvb-boxes, and other devices, but normally they are not used at the same time.
So that definitely indicates that something is amiss. I suspect you have a VDSL connection to the internet? It's known that powerline modems interfere with DSL connections because a powerline modem is essentially a VDSL modem working on the power lines instead of copper phone lines, and of course that can bleed over onto the phone lines and you'll get interference like crazy. Also given the age of your house you might expect poor wiring.
You wouldn't detect a problem with iperf on the LAN since that doesn't involve the WAN, but when actually streaming off the internet, you'd of course potentially have the powerline equipment interfering with the WAN equipment and causing all sorts of hell, causing dropouts and de-sync of the ISP equipment.
Unfortunately, the 5Ghz will have even shorter range within your dense walled house.
Is it really absolutely impossible to run a cat6 to the location of the TV area? Sounds like you've got a device one floor down, running a cat6 up the wall from below, and through the floor sounds strongly tempting I have to say. Even when walls are made of stone, usually floors are wood joist etc. Once you have a cable there, you can put a switch and get as many devices as you need, such as additional wifi APs
In the absence of a cable, I suggest looking into 802.11s mesh based devices rather than WDS, mainly because WDS just didn't work well enough for me so my experience says stay away. The mesh can be used to provide a backhaul between APs and then you can plop APs down as needed. It might work well for your case and would be flexible. Search the forums for info on mesh.
@jeff is using 802.11 mesh + batman-adv to run several VLANs over a mesh backhaul if I remember correctly, he might know the right forum topic to read to get the overview. There have been a bunch of questions about this kind of thing in the last year or so.
That's correct. I'm running 4 or 5 Archer C7s with backhaul on 5 GHz and APs on both 2.4 and 5 GHz.
My current config is the basis of the present version of https://openwrt.org/docs/guide-user/network/wifi/mesh/batman
However, I've got to agree that
I have a Fritzbox 7390 connected, but don't know if this is VDSL, my ISP says XDSL. There is no way to have an ethernet cable at the room, where I need it. I think this needs 1 week work and a lot of dust and money. But I hope that 5GHz could work. The electricity cable in the ground floor are new, but in the 1st floor are very old. Nevertheless I tried home plugs, because you know the result only, when you test it.
I have 2 options in the 1st floor. 4-5m to a router below in the ground floor or 4-5m to a router in the 1st floor. The router in the ground floor is planned, in the 1st floor not. I assume there is no big difference in quality between these 2 places, but who knows. I think I have to test 5GHz, but 4-5m could work and the influence of the neighbours is smaller. Actually I don't know, what material is used for the floor, for sure wood, but I don't know what else. In another area I have better reception from 2 floors above without thick walls, than from 1 floor above with thick walls. It is trial and error.
I need a working configuration and I don't want WDS in any case. If it is not possible, then I will accept more than 1 SSID for the mobile phones.
Can you recommend a brand and a model for mesh? Because of all the mentioned problems, I want to test with the stock firmware before I use openwrt.and that is the next problem, because stock fw has less features normally. Please note Archer C7 are only available with v5 here, which is not supported.
"Stock firmware" is almost certainly unable to support 802.11s or advanced backhaul approaches.
You can implement B.A.T.M.A.N. over "ad hoc" networking, so the connectivity on an ad hoc network (without any "mesh" involved) will give you an idea of what you would be able to get with advanced backhaul approaches.
I assume xdsl and vdsl are both going to interfere with each other so this may be why Powerline does not work for you.
The issue you will have with mesh is in order to do a mesh solution you will need to support mesh on each of the access points. This means you need to purchase at least 2 compatible access points and have an ethernet cable connection to one of them. You might do well to find used C7 earlier versions. Otherwise I think just look at table of hardware for ideal for open wrt
https://openwrt.org/toh/views/toh_available_864
You might look at something like the gl-ar750, small and cheap and unobtrusive.
I did a little googling, and it seems xDSL is the generic term for any kind of DSL, VDSL is the highest data rate type of xDSL, which means the powerline interference with your WAN is very very likely the cause of your inability to stream from the internet.
So I guess that's problem solved, you need a WiFi solution, or you need a coax cable solution if you have existing coax somewhere you can use. Sometimes someone in the past has put in coax and you can reuse it for ethernet using "MOCA" adapters.