Hello everyone. Using version 3.13.234 on Android, when opening Survey123, the app always states "Your device is offline" if the phone is not connected on wifi, despite the fact that there is a cellphone connection and all other apps (including Esri apps such as Collector or Explorer) work fine.
It is possible to access the content of the app as long as we are connected to the wifi, and if a survey has been downloaded while on wifi, it will be possible to use it "offline" (once again, our devices are NOT actually offline...), but all the map-based questions are impossible to use. I know there is a way around this but this is not what I want, especially since it is used to locate points based on the cellephone's GPS.
We do not use a VPN on our phones and two other people have the same issue as me (I actually did not have this issue but when they came to me, wanting to see what was going on, I uninstalled and reinstalled the app and now have the same issue as them). The app has all permissions I can grant it on my phone and is allowed to use mobile data.
I've regularly encountered this with my users, and have had a number of solutions that both work and end up failing. The most common resolution is to use one of or a combination of mobile wifi devices, offline enabled surveys, the S123 app vs. the website on mobile data, and/or different share settings as you had mentioned alongside resets, updates, etc. The most common answer from other S123 survey designers that I found was that it was device specific, which usually ends up being the case anyways among IT driven answers outside user error on the survey users who go and fill in the survey on mobile devices. If you are in a building or near trees the survey can go into offline mode for the simple GPS parameters of being unable to lock onto the minimum number of GPS satellites in the network. A workaround that my users have found useful is to preload the survey with location being manually selected before entering a GPS poor zone or where internet and cell data falls off the map. However in cases where this is needed to be done automatically it is usually safe practice to pair with a mobile survey grade GPS receiver, wifi hotspot puck, or other signal amplifier device if you can't get offline mode to work. Naturally if none of these end up helping you or if they are outside your desired workflows, you can always open an ESRI ticket via you organization or ESRI login to work towards a resolution tailored for you specifically. Hopefully this helps narrow down your search, it's a common issue and I definitely sympathize with you in your struggle.
Best regards & God bless,