Thanks for trying to help and for quick replies! I have already bought a new one because nowadays it is difficult to live without internet ;) and I will return the old one. Thanks to the 3-year...

@Kevin_Z OK, so... 1. Link with beta version is from Your post #11 https://static.tp-link.com/beta/2021/202102/20210208/beta_mr6400v2_en_2018-10-30_update.zip 2. Yes, I can't set internet via LTE...

@Kevin_Z please help me ... after uploading this beta version, my MR6400 stopped working, half of the options are unavailable (fields or entire pages are not shown) including LTE which does not work...