I am trying the github instructions on Proš but struggle at adding the repos.
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I have these Timeout errors too, from the "flathub" repo. From the look of it, "kdeapps" repo looks good. I tried from different networks and VPNs thinking my network was be the culprit, but it certainly wasn't the case.
Anyway, I did install the kde-arm-Qt-5.12 runtime and then the Angelfish on phone. I flatpak installed the org.kde.Platform/arm/5.12 in PC and copied the runtimes to the phone under ~/.local/share/flatpak/runtime/. Installing Angelfish from kdeapps repo went *mostly* fine then on Sailfish the normal way.
I observed that the flatpak wouldn't throw the timeout error when accessing flathub if the install/repo-sync operation was carried out quickly after a fresh Sailfish restart. It starts to throw errors after that.
I have heard that Flathub has sometimes net issues, but usually its not too bad. I wonder now whether your phone enters suspend and looses connection because of that. In this case, the timeouts could come with switched off screen, but not with display on.
Happy lal has similar to tell
I thought i was stupid over the last 2 evenings
But yes, it looks like network issues and i had the same thought and tried with display on while charging and usb plugged in.
Can also confirm the kdeapps repo not throwing errors.
Also tried to switch wlan off and get repos from mobile data, same.
Standing by for debug instructions
TBH, I have no clue the downloads fail. Could be probably many reasons behind it. Maybe something is with infrastructure of Flathub leading to it. But a trick that @lal used should work for you too. If you have PC nearby