Glitches in airplane mode

I've been experiencing a few issues when using the app in airplane mode; I have two Android devices, and this happens only on one of them.

First, some articles load only partially, or take several minutes to load completely. For example, I saved this article to Wallabag: https://www.nytimes.com/2021/06/30/sports/tennis/wimbledon-grass-court-safety-serena-williams.html
When I switched to airplane mode and tried to read it, only the first two paragraphs showed up, followed by Loading... After several minutes, the rest of the article loaded.

Second, my reading position either isn't saved or is very slow to load in airplane mode. That is, if I do the following in airplane mode:
1. Pick an article and read it partway
2. Go back to list of articles
3. Select the previous article
I'm shown the beginning of the article, not wherever I read to before. If I continue reading for a few minutes, the position jumps, as if it's trying to return me to the saved position.

# Environment details
- **wallabag app version**: 2.4.3 (229)
- **wallabag app installation source** (e.g. Gplay, F-Droid, manual): Google Play
- **Android OS version**: 6.0.1
- **Android ROM** (e.g. stock, LineageOS, SlimRom,…): stock
- **Android hardware**: Nexus 7
- **wallabag server version**: wallabag.it

I also have a Pixel running Android 10 which doesn't experience either of these issues. I totally understand if it's not worth the effort of fixing an issue that seems to be due to a super old Android version, but I figured I might as well ask, since I really enjoy prefer using Wallabag on the Nexus 7.

Thanks for all of your hard work in building this app!