Plexamp fails to connect on cellular network

Plex Media Server Remote Access
,
1

Server Version#: 1.43.3.10828
Player Version#: Plexamp iOS v4.12.4

Plexamp iOS app is unable to connect to the server when using cellular data. It is able to connect fine via Wi-Fi, Wi-Fi w/ VPN, and cellular data w/ VPN. The regular Plex app has no problem connecting via cellular. I also used had this problem when I tried the Plex Dash app a while ago and just gave up trying to use the Dash app.

The server is running on Synology through a reverse proxy with the custom server access URL set but remote access disabled in the server settings as I only want to be able to access this through the reverse proxy.

Plexamp logs and regular Plex app logs provided.

com.plexapp.plex 2026-07-16–17-41-04-365.log (15.2 KB)

Plexamp.log (192.1 KB)

2 
Jul 16, 2026 13:25:49.152 [Javascript] WARNING - DEVICE: Server connection https://plex.ndlx.ca:443 didn't work for Saturn: HTTP status -35

It can’t reach your server.

CURLE_SSL_CONNECT_ERROR (35)

A problem occurred somewhere in the SSL/TLS handshake. You really want the error buffer and read the message there as it pinpoints the problem slightly more. Could be certificates (file formats, paths, permissions), passwords, and others

3

So why would this be an issue that only occurs on a cellular data connection, and only with Plexamp and Plex Dash? It’s perfectly able to communicate with my server otherwise, and the Plex app connects fine over cellular.

4

I don’t have an answer for you, perhaps Plex is connecting over a relay or something. Maybe something is sitting between Plexamp and the server with strict/different TLS requirements.

5

Relay is disabled on the server. The Plex app is able to connect and play media via cellular data, the browser is able to connect and play media via cellular data (both movies/tv and music), Plexamp is unable to connect which in my mind indicates an issue with the Plexamp app and the way it’s handling the cellular connection.

6

Who is terminating SSL?

7

I’m not sure what you mean?

The Synology is running a reverse proxy on port 443 with a certificate from Lets Encrypt. Plexamp is able to connect to it with no problem when I’m on wifi or using a VPN on the cellular connection. It only has an issue when connecting purely on the celluar data.

8

Reverse proxy means it’s terminating the SSL connection. For some reason it and Plexamp don’t agree. Not sure why.

9

Yeah I’m not sure what’s going on with Plexamp.

The regular Plex app connects fine to the reverse proxy domain:

[Connections] Testing connection for Saturn at https://192-168-2-19.722aee565fa048de98228e11eeff3a7c.plex.direct:32400
[Connections] Testing connection for Saturn at https://plex.ndlx.ca:443
[Connections] GET 200 https://plex.ndlx.ca:443/media/providers 180ms
[Connections] Current best connection to Saturn is https://plex.ndlx.ca:443

But Plexamp is actually failing to connect to that domain even when using my local network (which has the domain pointed to the local IP of the machine) and falls back to using the plex.direct URL.

Don’t know if this is relevant, but Plexamp is also receiving a 404 error every time it tries to connect to plex.tv:

Jul 17, 2026 00:34:21.197 [0x6c633000] DEBUG - Networking: Completed request 289: (GET https://plex.tv/api/v2/user/settings?uuid=ce17cee8e896cb60&key=RecentPlays&cacheBuster=1784262861132) with code 404 (have 105 bytes) in 48 ms.
10

Same failure here, with a slightly different error code — adding data in case it
helps narrow it down.

Setup: Plexamp iOS 4.12.4, PMS 1.43.3.10828 (same server build as OP).
Plex connects directly, no reverse proxy in front of it.

Symptom: identical pattern — fine on WiFi, fine on WiFi+VPN, dead on cellular
alone. My error is -28 (CURLE_OPERATION_TIMEDOUT) rather than OP’s -35.

What I think is the useful part: Plexamp’s own logs show it trying all 4
published connections (LAN, IPv6, public, relay) and every one timing out at the timeout — 15.00 s direct, 25.00 s relay. The same app successfully reached plex.tv, sonos.plex.tv and itunes.apple.com on
443, each returning 200 in 400–800 ms. So the app has working network; it is
specifically the connections to the server that hang.

I also confirmed the server is reachable on that same cellular
connection: mobile Safari loads /identity over cellular fine, and Plex for iOS
connects and browses normally. Only Plexamp fails. Server-side logs show those
requests arriving, so nothing is being dropped before it reaches the origin.

Disclaimer: the following is speculative AI analysis of the issue based on my iOS Plexamp logs and my plex server configuration. But I hope it could be helpful for developers investigating the matter.

My carrier is IPv6-only with
464XLAT/NAT64 (T-Mobile US). Plexamp bundles its own libcurl (7.74.0, per its
log) while Safari and the main Plex app use Apple’s URLSession — and Apple
documents that apps which bypass the system resolver or use IPv4 literals fail
specifically on DNS64/NAT64 networks. That would explain why only Plexamp is
affected, and why a VPN fixes it. Are others hitting this also on IPv6-only
carriers? Worth checking, since it would be an easy pattern to miss.

Worth noting it doesn’t look like simple carrier port-blocking either — there are
two other threads where this happens inside a Tailscale tunnel, with a direct
connection and healthy RTT, where the carrier can’t see the port at all:

  • /t/plexamp-works-on-wifi-via-tailscale-but-not-on-cellular/938958
  • /t/plexamp-ios-times-out-28-on-cellular-over-tailscale-safari-succeeds-at-same-url/939215