new user here, i need help cause i dont know what else to do
hi, sorry for the broken english is not my main language, just like the title says im a new user who is trying linux for the first time, made a partition on my disk to try pop!_os but i have been running into some problems
first, my laptop is an Asus Vivobook 15 M1502QA that has a MediaTek Wi-Fi 6E MT7902 Wireless LAN Card, my first problem entering pop!_os was that my wifi wasnt workin, tried varius things but nothing worked so i purchased a TP-Link Archer T2U Nano (AC600) (it is what was available in my city for USB wifi adapters (small city in argentina) and i didnt want to spend a lot of money in an adapter i didnt know it was gonna work, in first instance it worked but it started having some problems like the speed going from ~84 Mbps to ~5 Mbps shortly after starting and spontaneously roaming from 5 GHz to 2.4 GHz and NetworkManager ignoring the forced BSSID, always falling back to 2.4 GHz. (everything being done in the terminal) after that i used pop!_os wifi interface to force 5 GHz, bssid and channel and that seemed to have worked but the same problem that the speed dropped kept happening, when i restart i have to do almost everything again cause it doesnt connect to the network after restarting and i have to forget the network and do the configs once again, i dont know what else to do, only tried pop!_os and fedora in live.
heres a summary of what have i done with the help of claude and chatgpt cause i went in linux with little to 0 knowledge
## Full Technical Summary of Your Case
### Hardware and Environment
Component | Detail
-------------------|----------------------------------------
WiFi Adapter | TP-Link Archer T2U Nano (AC600)
Chip | Realtek RTL8821AU
Active Driver | rtw88_8821au (kernel native)
Interface | wlx98ba5f23bea8
OS | Pop!_OS, Kernel 6.18
Router SSID | /////// (dual band, same name on 2.4 and 5 GHz)
---
### Identified BSSIDs
Band | BSSID | Frequency
--------|--------------------|-----------------------
5 GHz | 20:///////:66 | 5745 MHz (channel 149)
2.4 GHz | 20:///////:65 | 2437 MHz (channel 6)
---
### Main Problem
Speed drops from ~84 Mbps to ~5 Mbps shortly after starting.
The adapter spontaneously roams from 5 GHz to 2.4 GHz, and
NetworkManager ignores the forced BSSID, always falling back to 2.4 GHz.
---
### What Was Attempted and Results
Action | Result
------------------------------------------------|------------------------------------------------
Compile external drivers via DKMS | FAILED — incompatible with kernel 6.18
Create rtw88.conf + update initramfs | PARTIAL — did not fix roaming
Fix BSSID from Pop!_OS GUI | IGNORED — reverted to 2.4 GHz
nmcli connection modify with BSSID | FAILED — broke auto-reconnect on reboot
nmcli device wifi connect with explicit BSSID | IGNORED — connected to 2.4 GHz anyway
iw dev ... set power_save off | OK — applied (requires sudo)
udev rule for power management | OK — created
iw dev ... scan to inspect BSSIDs | FAILED — requires sudo
---
### Current State
- Connected to 2.4 GHz (20://////////:65) with bitrate 65/6 Mbps — heavily degraded
- The adapter CAN connect to 5 GHz (confirmed once: 292 Mbps VHT 80MHz)
- Core issue: preventing NetworkManager from choosing 2.4 GHz
---
### Most Likely Root Cause
The router has the same SSID on both bands and the RTL8821AU chip
sees the 2.4 GHz signal as more stable (-50 dBm vs -62 dBm on 5 GHz),
so NetworkManager always prefers 2.4 GHz regardless of the configured BSSID.
BSSIDs :65 and :66 are consecutive MACs, typical of dual-band routers.
thank you in advance, all suggestions are welcome !