@Akapol
Thanks for reaching out to us.
May I know what is your SIM card’s supporting band?
You may try to change to a different band on your router and see if signal strength will be better.
How to select 4G band manually on the web interface of LTE Gateway Routers?
If no help, please provide me a screenshot of status page of router web management interface.
How to log into the web-based management interface of TP-Link Wireless 4G LTE Router?
After you login, please go to Advanced>>Status>>take a screenshot of Status page.
And please also look at the bottom of the whole management page, then tell me what is the hardware and firmware version of your device. Thanks~