I have the same issue and have already reported it to Tesla, but I don't think they can/will do much about it. What I am hoping to get is a better understanding of how the communication between the app and the car works to help troubleshoot this.
So here are the basics:
HW: Samsung Galaxy S22 Ultra with Android 14, and a Model 3 on 2023.44.8 (though the issue is not tied to getting this update, is pre-existing).
Background: ever since I changed my internet service provider in mid-November I've been having this issue. No other hardware changes beside the modem of the ISP, so my Wi-Fi router (TP-Link Archer AX55 w. firmware 1.2.6), phone, firewall settings have not changed a bit. The new cable modem is actually not even a traditional modem, it is an optical network terminal Teletronik GE 2112 with no wifi, just a single fiber-optic port and a gigabit LAN port to the router. I can't find anything about this on the internet, but the German company/brand seems to be in the pro networking equipment business.
Issue: I am unable to wake up the car once it went to "deep sleep" i.e. several hours not used, if my phone is on Wi-Fi. The Tesla app (v4.28.2-2157) shows a "401 session expired" message and the controls do not work, can't pre-heat the car from my phone or open doors, etc. Also, the profile picture and the referral box icon on top of the app do not load either. HOWEVER, if I switch back to LTE on my phone, the car wakes up instantly, profile loads int he phone app, and after that I can now turn WiFi back on my phone and everything works absolutely fine until the car goes into deep sleep again.
Root causes excluded:
This is highly unlikely to be an issue with the car, the phone/Android, or the Tesla app as things work just fine when the phone uses the 4G LTE network, and also every other app works fine on Wi-fi. Also, once the car is awake, things work fine over Wi-Fi as well:
- If this was an issue with the car's LTE or Wi-Fi connection, it wouldn't go away just because I switch my phone to LTE instead of Wi-Fi.
- Unlikely to be an issue with the Tesla app or Android itself for the same reason, plus that every other app works fine on Wi-Fi.
- We have also tried with another phone in the household and we found the same problem.
My first thought was that this could be an issue with the dynamic IP address I get from the ISP, as it could be blacklisted by Tesla due to previous automated attacks they could have gotten from this range of IP addresses. I had one issue with a hotel's site not loading properly, booking not working since i switch to this ISP, and they told me this is a known issue as many hotels use a particular foreign web hosting company and for some reason that company blacklists their IP address range. They couldn't get them to fix this yet.
HOWEVER, if this was the case with Tesla as well, access to the car wouldn't just magically resume to work over Wi-Fi (i.e. this same ISP) once the car had been woken up.
For the same reason I have excluded issues with my Wi-Fi router's firewall as well.
Current hypothesis:
My only logical conclusion is that, yes, this is obviously related to my ISP change, as the issue started immediately the day I switched over. However it cannot be a general IP address-range blacklisting on Tesla's side, or some general setting on the ISP's side blocking access to Tesla's servers.
My thinking is, that there is something different about the way the Tesla mobile app re-establishes connection with Tesla's servers once the old session timed out vs. all the other communication it does later on. Maybe it uses another protocol, maybe it accesses another port, but it feels like that specific message, to log in to the server, is blocked by my ISP by either by a setting on their equipment in their server room, or the specific optical network terminal they give to their customers.
Any inputs, thoughts, especially from people with deep IT networking knowledge would be appreciated, so I could help my ISP troubleshoot this. Obviously i have already called them, but the technician had no idea where to start and sent me to Tesla.... I imagine Tesla will close my ticket and send me to the ISP...