Hello @Amp_95 and welcome.
The RSRP-value looks fine so far, RSRQ on the other hand looks bad. Here are enough specialists who could help you, but some of them aren’t native English speakers and they don’t dare to answer in English.
There is a special forum for English speaking customers:
https://hilfe.o2online.de/english-o2-community-69
As I don’t mind to make any faults in English, I can try to help you. Did you place your router at or nearby a window? Did you try any other position to get better Signal (espacially RSRQ)? If router is placed directly to a window: Does RSRQ look better, if you open the window? Do you’ve got a balcony, where you can place the router on it? (Just for testing) These are just some of the standard questions, so we can short communication so far and the experts can give any advice. As you receive Band 3 (1800 MHz) there should be sure a way to enhance the LTE-Signal via an special Antenna.
Greets
Gruß
Joachim