> 122.8 MB will be downloaded
>  libreoffice-6.4.7.2  117.1MiB                                  344KiB/s 03:04 [#########         ]  52.7%guix substitute: error: TLS error in procedure 'read_from_session_record_port': Error decoding the received TLS packet.
> substitution of /gnu/store/44h13hn5zssfppz67vydxcf95qsc8qfw-libreoffice-6.4.7.2 failed
> guix package: error: some substitutes for the outputs of derivation `/gnu/store/9f8sffldy39mprihx6xgrs7hys9j75jm-libreoffice-6.4.7.2.drv' failed (usually happens due to networking issues); try `--fallback' to build derivation from source
> --8<---------------cut here---------------end--------------->8---
> 

I often have the same problem when I do "guix package -u".
(Same error message, same package libreoffice, same derivation)
(Usually libreoffice, sometimes with other packages as well.)

I don't know the cause though.