I’m having ongoing issues with the Signal App not delivering some messages and occasionally failing to send media, even on strong Wi‑Fi and cellular data. I’ve already tried reinstalling the app, clearing cache, and checking notification and battery settings, but the problems keep coming back. I need help figuring out what might be causing this and what specific settings, logs, or troubleshooting steps I should check next to make Signal work reliably again.
I had almost the same issue with Signal a few months ago. Messages stuck on “sending”, media failing on both Wi‑Fi and LTE, while other apps worked fine. Here is what helped, step by step.
- Check battery and background settings
On Android:
• Settings → Apps → Signal → Battery → set to “Unrestricted” or “No optimization”
• Settings → Apps → Signal → Mobile data → enable “Allow background data” and “Allow data usage while Data saver is on”
If you use a vendor skin like Xiaomi, Huawei, Oppo, OnePlus, etc, check their “battery manager” or “security” app and whitelist Signal. Those vendors kill background processes pretty agressively.
On iOS:
• Settings → Signal → enable Background App Refresh and Mobile Data
• Settings → Battery → disable Low Power Mode during testing
-
Notification and network permissions
On Android 13+:
• Settings → Apps → Signal → Notifications → ensure “Allow notifications” is on
• Settings → Apps → Signal → Permissions → allow “Nearby devices” or “Local network” if present
Some devices block networking in the background if permissions look odd. -
Check for VPN, firewall, DNS apps
If you use AdGuard, Blokada, NextDNS, NordVPN, Mullvad, company VPN, etc:
• Temporarily disable it
• Test sending a text and a photo to a contact who is online
Some VPNs or DNS filters block Signal’s CDN for media. I had media fail only when connected to Warp. Wi‑Fi looked strong, but Signal traffic got throttled. -
APN and carrier issues
On mobile data, try:
• Settings → Network → SIM / Mobile network → Access Point Names
• Reset APN to default
If your carrier uses IPv6 only or CGNAT, Signal sometimes behaves weird with flaky handoffs between 4G and Wi‑Fi. As a test, send a few photos while you are on Wi‑Fi only with mobile data off, then the opposite. -
Wi‑Fi router settings
On your home router:
• Turn off “Firewall strict mode” or any “Parental control” for your device
• Disable DNS filtering temporarily
• Change DNS to 1.1.1.1 or 8.8.8.8
• If your router has QoS, make sure your phone is not on a throttled profile
You can also test with a totally different Wi‑Fi, like a friend’s house or a coffee shop, to see if the problem stays with your phone or your home network. -
Inside Signal settings
In Signal:
• Settings → Data and storage → set “When using mobile data” and “When using Wi‑Fi” to “Always” for media auto-download, at least while testing
• Turn off “Use system proxy” if enabled
• Check “Network” related toggles if you use Signal beta -
Blocked or stale sessions
If issues happen with specific contacts:
• Open that chat
• Tap their name → “Reset secure session”
• Ask them to do the same
Sometimes an old session or linked device on their side delays messages. -
Linked devices
If you have Signal Desktop or on another phone or tablet:
• On your phone → Settings → Linked devices → unlink everything
• Test sending/receiving again
A stuck desktop client on a bad connection messed things up for me before. After re-linking, media started to send normally. -
Test with another account
If possible, install Signal on a second phone or a tablet with a different number:
• Send messages between your two accounts on the same Wi‑Fi
If one works and the other does not, it points to something with your device setup, not your network. -
Grab a debug log for Signal support
In Signal on your phone:
• Settings → Help → “Submit debug log”
• Copy the link and send it to Signal support with a short description, like “Messages delayed 5–30 minutes, media fails 1 out of 3 times, on Wi‑Fi and LTE, device X, Android/iOS version Y, started around date Z”
Their support sometimes spots failed connections to specific endpoints, or known issues with certain carriers or ROMs.
If you want to narrow it down fast, I would start with:
• Disable VPN / DNS apps
• Whitelist Signal from battery optimization
• Unlink desktop
• Test on a different Wi‑Fi and mobile network
Post your device model, OS version, carrier, and whether you use VPN or custom DNS. People here can match that against what has worked for them.
Couple of extra angles you can try that @suenodelbosque didn’t really dig into:
-
Check if it’s actually delivery vs notification
Sometimes Signal silently delivers late because of timestamp / clock issues.
• Make sure your phone’s time is automatic (network‑provided time and time zone). A wrong clock can mess with Signal’s queues more than you’d expect. -
Look for a pattern in who and when
Pay attention to whether:
• It’s mostly group chats vs 1‑to‑1
• It happens more with people who use linked desktop clients
• It’s worse right after waking the phone from sleep or switching Wi‑Fi ↔ mobile
If it’s mostly groups or people with desktops, it can be a session sync issue on their side, not yours. -
Check media specifics
When media fails:
• Is it only videos over a certain size / length?
• Is it mainly HEIC / very high‑res camera pics?
Try sending:
• A tiny compressed image (screenshot)
• A short video recorded in low resolution
If tiny stuff goes through instantly and big stuff dies, that points to connection reset or ISP/CDN weirdness, not generic “Signal is broken.” -
Try toggling IPv6 / Wi‑Fi calling / private DNS
This one’s a bit more nerdy:
• Disable Wi‑Fi calling in your phone’s Network settings and test again
• Temporarily switch Private DNS (if you’re using it) to “Automatic”
• If your router or carrier has an “IPv6 only” vibe, see if you can turn IPv6 off on your phone or router just to test
Signal sometimes behaves oddly when a flaky IPv6 path exists and IPv4 is fine. -
Rule out flaky SD card / storage
On some Android phones, if Signal is installed on adoptable storage or media is being written to a sketchy SD card, media sends can randomly fail.
• Ensure Signal is installed on internal storage
• If you use an SD card, try temporarily removing it and then test sending photos. -
Check for ROM / root / system mods
If you’re on:
• Custom ROM
• Rooted device
• Something like Magisk modules, NetGuard, AFWall+, etc
Those can interfere at a lower level than the VPN / DNS apps that @suenodelbosque mentioned. Disable modules / firewalls one by one and test. -
Compare with a different messaging app under the exact same conditions
Not just “WhatsApp works in general,” but:
• Same Wi‑Fi
• Same moment
• Same size photo/video
If Signal fails a 10 MB video while Telegram / WhatsApp succeed at the same second on the same network, that’s very useful info for Signal support and hints at their backend route from your ISP. -
Make a very controlled test and write it down
Example test script:
• Turn off VPN, Wi‑Fi calling, and Private DNS
• Stay only on Wi‑Fi, no mobile data
• Send: 10 text messages, 5 images, 2 short videos to a single contact who is online
• Note exact time and which messages get stuck
Do the same on mobile data only. Having this written down helps a lot if you submit a debug log plus a description like “message 7 and image 3 failed at 14:23 on Wi‑Fi.” -
Ask one or two contacts to do quick checks on their side
Particularly the ones where messages are delayed:
• Have them update to the latest Signal version
• Ask them to remove any old linked devices they no longer use
• Have both of you “Reset secure session” after that and then test fresh.
If none of this changes the behavior, I’d absolutely grab a debug log right after a failed media send and open a ticket with Signal, but put very specific info in it: device model, OS version, carrier, country, Wi‑Fi router model, rough time of failures, whether groups or DMs, etc. That’s the only way they can tell if this is a known routing/CDN issue affecting certain ISPs or something uniquely broken on your setup.
Also, it sounds weird, but try a completely different physical location and network (work, a friend’s house, coffee shop). If Signal suddenly behaves perfectly there, your “strong Wi‑Fi” at home might still be doing something odd under the hood even if speedtests look fine.