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I have built a prototype in an aluminum casing that works perfect when I am at home. I've measured the wifi radio signal with wavemon and the readings are perfect, lot's of range and a strong signal. 

In order to avoid Wi-Fi channel "duplicates" in the harbor, I've scanned the harbor for channel usage and I have chosen a channel that is not being used.
However, I cannot always logon to the access point that the raspberry is broadcasting. Sometimes it says "authentication failure, wrong password, or cannot login to this network."

The problem is only sporadic, doesn't happen always. However, I do have to point out that I have a steel boat. But, in the past, all Wi-Fi access points from any device did not have any problems at all. My understanding is that metal blocks the signal more than polyester, so much is true, but... I don't need to broadcast through any walls as the raspberry is directly in the cabin. Even when I am next to the raspberry and I lay my phone or tablet directly on it, it will not connect!

When I am further away from my boat, or at home it works instantly. I have no power problems, power supply is very stable and powers sufficiently. I've even tried removing the top lid of the casing to see if this was the cause. Also, when sailing out of the harbor, the problems persists.

So far, I have tried numerous places on the boat and found one that works. Outside of the boat on the sprayhood, I can connect, and then I can bring the pi inside and it will stay connected? 

I have been in IT for over 14 years, no radio expert but I have been too close with "my nose" to this problem and looking for some fresh opinions from you guys.


What I will now try to do is:

- transfer the pi to another casing
- try the sd in a pi that i know will work
- try a pi4 instead of a 3b+

I was wondering if any of you guys have anymore ideas. Also I have a question, some harbors are really a nightmare with Wi-Fi. Lot's of interference from all the masts and steel, and lot's of existing signals so that you cannot "join in" with your extra AP. I am starting to think that Wi-Fi is not the best system anymore for a headless system and wondering if there are alternatives, maybe Bluetooth, or even LoraWan? But then, how would I broadcast the webservers and RDP?

Hope any of you guys have any experience with above, looking forward to your stories.  (and support) Wink
It's annoying. It's very bothersome when the wifi fails and you don't know why. In my previous marina I was very bloody and finally discovered that there is a hidden powerfull radar from the police that generates interference.

In your case the interference seems to travel with you so I thought I'd suggest two things. The first is to try a different wifi usb unit to see if the behavior changes and compare results.

The other is to see if any of your electric or electronic devices could be the origin of your problems.

Just to give you some ideas.
(2020-07-20, 05:48 PM)monos1 Wrote: [ -> ]It's annoying. It's very bothersome when the wifi fails and you don't know why. In my previous marina I was very bloody and finally discovered that there is a hidden powerfull radar from the police that generates interference.

In your case the interference seems to travel with you so I thought I'd suggest two things. The first is to try a different wifi usb unit to see if the behavior changes and compare results.

The other is to see if any of your electric or electronic devices could be the origin of your problems.

Just to give you some ideas.

Thanks monos1 for your thoughts! Our harbor has ALOT of wifi range expanders to boost their marina access points, this could be part of the problem. I guess in my case it would be a combination (it's never simple haha). I've indeed tried to exclude the things I have control over, like shutting down everything on my boat that is broadcasting, this didn't have any effect. But, I didn't turn off my battery charger, so this I will try next time when I am there. 

But, I must say last time when out on the water, my engine was running and I guess the alternator emits it's own magnetic field. In this situation all other devices worked, except for the pi in the alluminum casing.
A known problem with the Pi4 is interference between the USB3 port and 2.4G Wifi. Is there any way you can try 5G wifi and see if there is any change? Alternatively, if you are using a wifi dongle for your AP, try putting the dongle on a USB extender cable.
(2020-07-21, 02:28 AM)abarrow Wrote: [ -> ]A known problem with the Pi4 is interference between the USB3 port and 2.4G Wifi. Is there any way you can try 5G wifi and see if there is any change? Alternatively, if you are using a wifi dongle for your AP, try putting the dongle on a USB extender cable.

Thanks abarrow,

I'll try the 5G, good idea. Also, I do have an external USB connection on the outside of the casing powered seperately. I have connected the dongle on it, but the network settings on Openplotter 2 will not let me use that for the AP. It does work and is recognized by raspbian buster, I can connect it and use it for internet, but not as an AP. I can choose the internet sharing device, but this will not make any difference and will keep choosing the built in WiFi chip as the AP. Any ideas on how I can configure that in OP2?
Tried 5G configuration (clicked the edit button, then checked the 5G box, channel 48 is automatically set, saved and rebooted) Openplotter saves this configuration, but when I login with Windows into the AP, I get the following details:

Protocol: Wi-Fi 4 (802.11n)
Security type: WPA2-Personal
Network band: 2.4 GHz
Network channel: 9
IPv4 address: 10.10.10.78
IPv4 DNS servers: 10.10.10.1
Manufacturer: Intel Corporation
Description: Intel® Centrino® Advanced-N 6205
Driver version: 15.16.0.2
Physical address (MAC): 8C-70-5A-1E-77-44

Either this data is wrong, or it did not apply 5G. I tried this on a 3B+, so maybe it's not supported on this.
I'll keep trying with the external dongle, or see if a Pi4 makes a difference.


___

Edit: found this thread about 5G on 3B+ has something to do with country code, if you set it to US it might work: https://github.com/raspberrypi/linux/issues/2619
Edit 2: Nope... doesn't work, it is saved correctly in wpa_supplicant, but it will not startup the 5G, will try to get the dongle up and running.
Edit 3: Tried iw list command, and see the supported frequencies for 5G (5000 mhz range, source: https://en.wikipedia.org/wiki/List_of_WLAN_channels) some of those frequencies in that range are disabled, so I will try another channel. Some have 20db as a spec but some also have IR and radar detection???.
Edit 4: The IR and radar detection are not supported, when choosing high channels with 5G, devices cannot connect anymore. Reverting changes to 4G again.
Unfortunately, only the RPI4 supports 5G wifi on the board. You could plug in a 5g dongle.
(2020-07-21, 12:39 PM)abarrow Wrote: [ -> ]Unfortunately, only the RPI4 supports 5G wifi on the board. You could plug in a 5g dongle.

Thanks, I'll try the pi4 when I have time to build it in.
I've got the dongle working on the 3b+, however I cannot get it to function as an AP. When I choose "use as internet sharing device" strange things happen:

- Choice: wlan0 (internal)
No AP is started anymore, both wlan0 and wlan1 will connect to my router
- Choice: wlan1 (external) 
AP is created, wlan0 still is the router internet connection and wlan9 is created as the AP.
wlan1 is still just a default connection that can connect to a router.

No matter what choice I make, wlan1 (external dongle) will not create an AP. Any ideas? I'd rather not do any manual configuration in hostapd files.
In regards to the AP not starting, I've found these two threads were helpful:

https://forum.openmarine.net/showthread....ht=hostapd
https://forum.openmarine.net/showthread....ht=hostapd

I can now experiment again with separate dongles again.

I have also found a possible explanation for the instability in the harbor:

- I was using an instable network mode, on board and AP together. It works perfectly at home, but this just is not stable enough in real life (harbor / steel boat) situations.
- On a 3B+ this is a problem, the exact same settings on a pi4 are working great.
- I will try the onboard setting only, using onboard or external as AP and will report back.

Right, still can't set the dongle as AP if I choose sharing internet device wlan0 or wlan1, but I think that the onboard WiFi is now stable enough to test it in the harbor again.
Just went out sailing, and can confirm that onboard + AP mode was the cause. Need to use the onboard one. This connection is stable and will keep connected.
Just need to figure out how I can set the external dongle to be the AP as no settings will let me do that. Any experience anybody?
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