I have a wifi link which is basically used to extend an ethernet connection (it runs wonderfully with an ethernet cable) through a wall where it is impractical to drill a hole etc. It is a dedicated link and not really used for anything else. Distance is about 5m.

The application is video streaming. I am struggling to get it to go above 7 MB/sec (measured on a high-end win10 laptop connected to the "destination" wifi device and transferring a huge file from a PC on the LAN). This seemingly translates to being able to smoothly stream a video rendered to about 15 mb/sec. (Yes. Megabytes and megabits). Now, obviously 7MB/sec is 56 mbps which is way more than 15 mbps, but it isn't that simple because of a lack of buffering in the system, and I suspect the video bit rates are "average" ones...

The "access point" is a Draytek AP800 which was not exactly cheap.
The other end is a Cisco WAP4410N AP running in a LAN-wifi bridge mode, also called "client mode", called by Draytek "Wireless Client/Repeater" (the end device is a Humax T2 video recorder with an ethernet interface and driving an HD TV via HDMI) and that was even less cheap.

I initially tried to use the AP800 in that mode (it is generally called "client mode") too but there was a very subtle problem which enabled the device connected to it to see the internet but not the local LAN. I spent a couple of days on this, without success... I finally suspected it was implementing some large MTU value and not supporting the UDP-based MTU negotiation. If I dropped the attached device's (a XPS13 laptop, win10) ethernet interface MTU from 1500 to 1000 it worked better. Hence I went to the WAP and that worked immediately, in its client mode.

I have done the following already:

1) Fixed the channel to 802.11n (not b/g/n)
2) Selected the channel to an empty space on the wifi analyser (currently 13)
3) Moved the two devices as close to each other as possible
4) Orientated their antennae in the same way (horizontal)
5) Moved them around to get the fastest speed (this seems heavily location dependent in the room; I can get anything between 1MB/sec and 7MB/sec).

but I need to get about a 2x further speedup.

I have seen the following settings in the Draytek AP, and in the Cisco:

http://peter-ftp.co.uk/screenshots/20181230033563017.jpg

http://peter-ftp.co.uk/screenshots/20181230493551717.jpg

Is there anything which can be tweaked there?

I believe going to 5GHz would speed things up a bit but (a) I am trying to make use of these two boxes which were anything but cheap and (b) I know that a cheap 5GHz device is not necessarily fast if it uses a slow CPU, and most consumer stuff does use low grade hardware. And nearly all of it runs Linux... (I am embedded system hardware and software designer).

Second part of the post (there is a 3000 char limit):

Between the two devices there is the brick wall (so about 15cm thick) and the rest of the distance is just air. It should be easy. I have a "wifi spectrum analyser" app on my android phone (used to see which channels are occupied, etc) and this shows a very strong signal at the receiving end.

Another option I have is a Ubiquity (pricey) access point up in the loft, covering the whole house. This is 2.4GHz + 5GHz but the 2.4GHz signal is a lot weaker at the relevant place. The 5GHz signal (ch 36) is obviously weaker still and e.g. my XPS13 laptop doesn't connect to it. Accordingly, when I use this AP for the video (this was the first thing I tried) the data link is noticeably slower. The most I was able to get was ~1-2 MB/sec.

If I can get 10MB/sec that will probably work fine. 15MB definitely will. This should be possible if the link can be forced to 40MHz.

The AP800 has these options
http://peter-ftp.co.uk/screenshots/20181231553584812.jpg
so I am on 20/40 "auto" which according to the Mikey app notes should select 40. However, this
http://www.tomshardware.co.uk/answers/id-2485539/link-reaching-wireless-speed.html
suggests that it will force 20MHz whenever it detects any other channels in use, so that's another dead end...

The WAP4410N (I previously called it WRT) has these options
http://peter-ftp.co.uk/screenshots/20181231013595212.jpg
but no matter what I select on the country menu I cannot get the 20MHz option to un-grey. Getting that to un-grey would likely help a lot, but how? Maybe there is other firmware for this box? The user manual (search for "40MHz") doesn't illuminate it. I have found that the 40MHz mode is settable when the WAP is in the normal AP mode, but it reverts to 20MHz and gets greyed-out when the WAP is set to the Repeater mode.

There is no metal in the brick wall. But it is brick, not a low density block. The signal level at the receiving end is high.

If I connect my XPS13 laptop directly to the AP800's wifi, and move it where there is a strong signal, the app-app data rate I get is 8MB/sec. This is about the same as the best achievable with the AP800-WAP wifi link... of course I can't tell whether the limit is in the AP800, or in the XPS13, but I think it is clear that the system is running at 20MHz, not 40.

Apologies for the long post. Perhaps someone can spot something... I do have another AP800 I could use, but as I said above it doesn't seem to work in the client mode.

An update, in case anyone is reading this forum - unlikely since it now needs a login, so almost nobody will find it on google... and Draytek don't read it.

I got a 1.5x speedup by replacing the WAP with a TP-Link WR802N. This has a "client mode" too. It does almost 11Mbytes/sec, and that is with the Draytek AP800.

It is a bastard to configure because in the default mode (access point) it bizzarely cannot be configured via ethernet. TP-Link actually say so, too. So basically you have to do a factory reset on it, then set the laptop (in the usual way) to a fixed IP of 192.168.0.x (where x is something more than 1) and connect to the device's wifi using the wifi credentials printed on its outside label. Then point a browser to 192.168.0.1 and you get the config menu, with login credentials of admin/admin. Then there is a wizard for setting up the Client Mode, and this actually works.

It gets more tricky if you want to set it to 40MHz. You have to do it in the default (access point) mode; the setting is not accessible in the client mode (which is dumb). Only after doing that can you go to the wizard and select the Client mode.

Due to the catch-22 of losing the access as soon as the wifi config is changed in any way, the Client mode can be finally set up only with the wizard. I don't think there is any other sequence, because in the Client mode you *cannot* connect to it via wifi Only via ethernet.

It is now doing the job, streaming the fast video as required.

What is really interesting is that connecting the top-end XPS13 laptop to the AP800 (using the XPS13's wifi) gave me 7-8 MBytes/sec while connecting the XPS13 to the AP800 via the WR802N (and using ethernet on the XPS13) gave me 11MBytes/sec. This really confirms that the laptop is not doing 40MHz on its own wifi, but the WR802N it was.

Not bad for such a cheap little box.

peter-h wrote: I have a wifi link which is basically used to extend an ethernet connection (it runs wonderfully with an ethernet cable) through a wall where it is impractical to drill a hole etc. It is a dedicated link and not really used for anything else. Distance is about 5m.

I need to do something similar ... because a 20" granite wall stands in my way.

I tried linking 2 x 2830n's together, but the throughput was pretty pathetic. I assumed I was going to have to go down the 'Powerline Ethernet' route, but I've just discovered a TP-link WR702N in my bits box, so I'll give that a try first.