LTE signal disappeared

For the last few years I have been using Telkom mobile as my internet at home. As soon as LTE was in my area I bought a B593 router from telkom. The signal was excellent in the beginning but slowly got worse. I now seldomly will get any LTE speeds and even 3g is not consistent with edge being the most common signal. I have set the router to use LTE only with no luck. I used to get over 30 Mbps. Now I'm lucky to get 4.