Discussion:
Bluetooth/SSH issue
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Charles Curley
2024-06-16 20:40:02 UTC
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On one of my machines, I have some interesting interference. Bluetooth
works just fine, and so does networking. Bluetooth is normally disabled.
However, when I have Bluetooth turned on (and after I turn it off), SSH
is *slow*.

I gather that the network controller is also the Bluetooth controller:

***@tiassa:~# lspci -vs 2:0.0
02:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8821CE 802.11ac PCIe Wireless Network Adapter
Subsystem: Realtek Semiconductor Co., Ltd. RTL8821CE 802.11ac PCIe Wireless Network Adapter
Flags: bus master, fast devsel, latency 0, IRQ 132, IOMMU group 10
I/O ports at 4000 [size=256]
Memory at 80500000 (64-bit, non-prefetchable) [size=64K]
Capabilities: [40] Power Management version 3
Capabilities: [50] MSI: Enable+ Count=1/1 Maskable- 64bit+
Capabilities: [70] Express Endpoint, MSI 00
Capabilities: [100] Advanced Error Reporting
Capabilities: [148] Device Serial Number 00-e0-4c-ff-fe-c8-21-01
Capabilities: [158] Latency Tolerance Reporting
Capabilities: [160] L1 PM Substates
Capabilities: [170] Precision Time Measurement
Capabilities: [17c] Vendor Specific Information: ID=0003 Rev=1 Len=054 <?>
Kernel driver in use: rtw_8821ce
Kernel modules: rtw88_8821ce

***@tiassa:~# uname -a
Linux tiassa 6.6.13+bpo-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.6.13-1~bpo12+1 (2024-02-15) x86_64 GNU/Linux
***@tiassa:~#

https://www.realtek.com/Product/Index?id=587

Is there some sort of cross-talk issue?
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Ryan Nowakowski
2024-06-16 23:20:01 UTC
Permalink
Post by Charles Curley
On one of my machines, I have some interesting interference. Bluetooth
works just fine, and so does networking. Bluetooth is normally disabled.
However, when I have Bluetooth turned on (and after I turn it off), SSH
is *slow*.
Is there some sort of cross-talk issue?
Sometimes Bluetooth and Wi-Fi share the same radio. Are you running ssh over Wi-Fi? Try running ssh over Ethernet while using Bluetooth. Is ssh still slow?
George at Clug
2024-06-16 23:30:01 UTC
Permalink
Rayan,
Post by Ryan Nowakowski
Post by Charles Curley
On one of my machines, I have some interesting interference. Bluetooth
works just fine, and so does networking. Bluetooth is normally disabled.
However, when I have Bluetooth turned on (and after I turn it off), SSH
is *slow*.
Is there some sort of cross-talk issue?
Sometimes Bluetooth and Wi-Fi share the same radio. Are you running ssh over Wi-Fi? Try running ssh over Ethernet while using Bluetooth. Is ssh still slow?
What do you mean by "Bluetooth and Wi-Fi share the same radio" ?

In the early days of Windows 8 Tablet and laptop devices, I noticed that the bluetooth mouse would move jerkily while a large download was happening over Wi-Fi. Many people had this issue, and it was so annoying it lead me to tell people not to use bluetooth mice.

You comment might explain why this problem existed, though I am still not sure what "share the same radio" actually means?

Thanks for your comment,

George.
e***@gmx.us
2024-06-17 01:30:01 UTC
Permalink
Post by George at Clug
Rayan,
Post by Ryan Nowakowski
Post by Charles Curley
On one of my machines, I have some interesting interference. Bluetooth
works just fine, and so does networking. Bluetooth is normally disabled.
However, when I have Bluetooth turned on (and after I turn it off), SSH
is *slow*.
Is there some sort of cross-talk issue?
Sometimes Bluetooth and Wi-Fi share the same radio. Are you running ssh over Wi-Fi? Try running ssh over Ethernet while using Bluetooth. Is ssh still slow?
What do you mean by "Bluetooth and Wi-Fi share the same radio" ?
There is some circuitry in the computer (the radio) that does both BT and
wifi (at least 2.4GHz wifi) in some cases, probably by toggling from one to
the other. They share the same frequency, or are close enough that the same
electronics works.

--
O freddled gruntbuggly
Thy micturations are to me
As plurdled gabbleblotchits on a lurgid bee. -- P. V. Jeltz
Jeffrey Walton
2024-06-17 06:00:01 UTC
Permalink
Post by George at Clug
Rayan,
Post by Ryan Nowakowski
Post by Charles Curley
On one of my machines, I have some interesting interference. Bluetooth
works just fine, and so does networking. Bluetooth is normally disabled.
However, when I have Bluetooth turned on (and after I turn it off), SSH
is *slow*.
Is there some sort of cross-talk issue?
Sometimes Bluetooth and Wi-Fi share the same radio. Are you running ssh over Wi-Fi? Try running ssh over Ethernet while using Bluetooth. Is ssh still slow?
What do you mean by "Bluetooth and Wi-Fi share the same radio" ?
In the early days of Windows 8 Tablet and laptop devices, I noticed that the bluetooth mouse would move jerkily while a large download was happening over Wi-Fi. Many people had this issue, and it was so annoying it lead me to tell people not to use bluetooth mice.
You comment might explain why this problem existed, though I am still not sure what "share the same radio" actually means?
Both Wifi and Bluetooth use the globally unlicensed Industrial,
Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band.

You can buy combo chips for the application. See, for example,
Qualcomm's QCA9377,
<https://www.qualcomm.com/products/technology/wi-fi/qca9377>.

Jeff

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