Is this normal behavior or do I have a weak bluetooth/wifi card?

Question

linux

I tried to figure it out myself for a long time, not a noob, but here I don’t know what to think anymore. There is a laptop (still "those" Sony Vaio bought for expensive, high-quality components), ubuntu OS.

Problem.
I connect headphones via bluetooth (total 1 device) - it plays clearly.
I connect a regular keyboard via bluetooth (total 2 devices at the same time) - the headphones again sound like they should.
I replace the keyboard with a Lenovo Thinkpad Trackpoint, which, moreover, is also a mouse (total 3 devices working at the same time) - headphones ... wheeze, whistle, you can listen, but this cannot last long.
I switch the keyboard to 2.4Ghz, thereby freeing the bluetooth card, so immediately the sound becomes clear. Ie 3 is already the ceiling? On amazon, this bluetooth card (Atheros AR5B225) costs from 2k rubles (25 euros), I wouldn’t say that it’s cheap, it should drag. The OS itself seems to be unaware that the quality is not so hot, because everything is ok in the logs. Who has any ideas? How many devices are connected via bluetooth at the same time?

ps I don't use wifi, only LAN, so the card is even unloaded for power.

Answer 1

In bluetooth, all connected devices (by the way, the limit is 8) operate at the same frequency and fumble one channel, if one of the devices does not work well (for example, poor reception, constantly require retransmission, etc., this should also affect the final speed
Did not find confirmation, but doesn’t bluetooth have the same speed limit as usb hub? (if there is a usb1 class device in the hub (up to 1 Mbps, usually these are mouse keyboards, etc.), then the speed of all devices in the hub is reduced to the same) Perhaps a specific device changes the bluetooth settings to 'bad'

Answer 2

A good device from 5k, I advise ASUS AC-55BT