Your router’s wifi speed is based on a 4G network. 4G network speed depends on signal strength, concurrent users connecting to the cellular base station, and data flow etc, please check as follows.
1. Check the Antenna Installation
Make sure antennas are installed on the correct sockets tightly; refer to the photos.
Please install the antenna on an open space without barrels, especially the metal material.
The wifi signal can be easily blocked by the other barriers, so please also walk near to the router and test again.
2. Check Signal Strength
Please refer to https://ezen.link/signal-test to check the signal reception.
The 4G router requires to input at least -101dBm 4G LTE signal (RSRP standard) or -75dBM 3G signal (RSSI standard).
If the signal is weaker than <95dBm, you can move to another location to get a stronger signal or upgrade to the high gain 4G LPDA antenna, refer to the link to know more details. https://ezr33.docs.outdoorrouter.com/v/ev3117/advanced/signal-tests/improve-weak-signal
3. Setting WiFi Output Power
You can try to set WiFi at a lower output power and 40MHz bandwidth to increase the speed. The higher output power brings a lower speed on a WiFi connection.
Go to Network-Wireless-SSID, click Edit, you can set the transmit power.
BTW, the European countries have limited the WiFi power to a lower level.
You can go to Go to Network > Wireless.
Click the “Edit” button on the 2nd row of the master SSID.
Click the tab of “Advanced Settings”, choose US or AU on the “Country Code”
Then you can set the WiFi output power to maxed level 30dBm on the General Setup tab if you need.
4. Upgrade WiFi antenna
You can upgrade the default wifi antenna to the high gain wifi antenna or connect a wifi extender/router to extend the wifi coverage.
WiFi antenna
https://www.outdoorrouter.com/product-category/outdoor-router-accessory/wifi-antenna/
WiFi extender
https://www.outdoorrouter.com/product/outdoor-mimo-wifi-extender-300mbps-poe/