What is the best way to check max read/write speed? Here is the output from lspci. Do you see anything strange?
00:00.0 Host bridge: Intel Corporation Device 4e24 00:02.0 VGA compatible controller: Intel Corporation JasperLake [UHD Graphics] (rev 01) 00:04.0 Signal processing controller: Intel Corporation Dynamic Tuning service 00:14.0 USB controller: Intel Corporation Device 4ded (rev 01) 00:14.2 RAM memory: Intel Corporation Device 4def (rev 01) 00:15.0 Serial bus controller: Intel Corporation Serial IO I2C Host Controller (rev 01) 00:15.2 Serial bus controller: Intel Corporation Device 4dea (rev 01) 00:16.0 Communication controller: Intel Corporation Management Engine Interface (rev 01) 00:17.0 SATA controller: Intel Corporation Device 4dd3 (rev 01) 00:19.0 Serial bus controller: Intel Corporation Device 4dc5 (rev 01) 00:19.1 Serial bus controller: Intel Corporation Device 4dc6 (rev 01) 00:1c.0 PCI bridge: Intel Corporation Device 4db8 (rev 01) 00:1c.1 PCI bridge: Intel Corporation Device 4db9 (rev 01) 00:1c.2 PCI bridge: Intel Corporation Device 4dba (rev 01) 00:1c.4 PCI bridge: Intel Corporation Device 4dbc (rev 01) 00:1c.5 PCI bridge: Intel Corporation Device 4dbd (rev 01) 00:1c.6 PCI bridge: Intel Corporation Device 4dbe (rev 01) 00:1c.7 PCI bridge: Intel Corporation Device 4dbf (rev 01) 00:1e.0 Communication controller: Intel Corporation Device 4da8 (rev 01) 00:1e.3 Serial bus controller: Intel Corporation Device 4dab (rev 01) 00:1f.0 ISA bridge: Intel Corporation Device 4d87 (rev 01) 00:1f.3 Audio device: Intel Corporation Jasper Lake HD Audio (rev 01) 00:1f.4 SMBus: Intel Corporation Jasper Lake SMBus (rev 01) 00:1f.5 Serial bus controller: Intel Corporation Jasper Lake SPI Controller (rev 01) 01:00.0 Non-Volatile memory controller: Silicon Motion, Inc. SM2263EN/SM2263XT SSD Controller (rev 03) 02:00.0 SATA controller: JMicron Technology Corp. JMB58x AHCI SATA controller 03:00.0 Non-Volatile memory controller: Silicon Motion, Inc. SM2263EN/SM2263XT SSD Controller (rev 03) 04:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04) 05:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04) 06:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04) 07:00.0 Ethernet controller: Intel Corporation Ethernet Controller I226-V (rev 04)
I have had these permission issues in the past. Once I switched to mounting directly in the LXC they all went away.