This provides a lot of information, but it only covers 2.4Ghz and SISO, which likely explains the 150Mbit claim. It’s very old technology and shouldn’t surprise you if you’re having trouble with those speeds.
My other computer (third model) includes a USB Wi-Fi adapter. I purchased it for under $20 new and it handles around 50 MB/s smoothly. The specific version is Realtek RTL8821AU Wireless LAN 802.11ac USB 2.0 Network Adapter. Updated February 11, 2021 by Steliosem06
It's truly sorry, but that isn't the USB Wi-Fi device I expected. The information on Device Manager matches what it displays. The actual model is listed here: https://www.plaisio.gr/anavathmisi-dikti...na_2741504
You’re taking the wrong approach: tossing items to see what sticks. This will likely result in a lot of costly adapters. Your ISP may have branded internet gear, but they’re typically produced by another manufacturer. Check the Sercom device for a model number. This helps identify the WiFi generation it supports and whether an upgraded adapter would be beneficial. Remember, interference significantly affects WiFi performance—what seems like “bad internet” is often just a matter of signal quality. Use WiFi Analyzer to perform a survey (show screenshot of the ‘Analyze’ page on both 2.4GHz and 5GHz). Also, capture the WiFi settings from the Cosmote webadmin interface.
I discovered some information about the device, which was originally translated from Greek. Speedport Plus provides everything needed for the app needing reliable internet connection (ISP). Its key features include VDSL2 with dual-band 2.4 GHz and 5 GHz 11ac, a touchscreen FXS, and compatibility with the newest professional ISPs in Europe. The device offers 4 Ethernet ports supporting speeds up to 10/100/1000 Mbps and one USB port. It also includes a WAN touch port for VDSL2/ADSL2+ and supports 2.4 GHz and 5 GHz 11n outputs, four Gigabit Ethernet ports, three RJ11 ports, one USB 2.0 port with seven LEDs and three buttons (WLAN, WPS, Reset). It supports Wi-Fi 802.11 a/b/g/n/ac.
These are the network configuration options displayed when you type your IP address into a search engine. They show details about your connected Wi-Fi network, such as the SSID and encryption settings.
Ensure you use the local IP address of the Speedport Plus in your browser. Go to the screens on pages 86 and 93 in the manual.