Symptom 1: QR won't scan / download fails
- Install on WiFi. Installing over cellular is the #1 cause of broken downloads.
- QR must be complete, sharp and focused; scanning a zoomed-in screenshot beats a tiny email image.
- Update the OS — old versions have occasional eSIM bugs.
- Still failing → manual entry: the "enter manually" option with SM-DP+ address + activation code gives the identical result.
- "Can't add" / "code already used" → the code is single-use and already consumed (maybe by an earlier attempt). Ask the seller for a fresh code — retrying won't help.
Symptom 2: Installed but no signal / No Service
- Confirm the eSIM line is turned on (easy to switch off by accident).
- Confirm data roaming is ON — iPhone: Settings → Cellular → tap the line → Data Roaming; Samsung: Connections → SIM manager → the card → roaming.
- Try manual network selection: turn off automatic selection and pick a local carrier — auto-selection sometimes gets stuck.
- Remove the physical SIM temporarily, leaving only the eSIM, to rule out dual-SIM interference; then restart.
- If the eSIM's partner networks simply don't cover the area, that's a coverage problem — check the coverage list on the product page before buying next time.
Symptom 3: Signal bars but no internet
- Confirm the plan has data left and is activated (fastest: ask the seller to check their backend).
- Check the APN: a few carriers need it entered manually — iPhone: Cellular → the line → Cellular Data Network; Android: Access Point Names. One wrong letter breaks data; get the exact value from the seller.
- Confirm mobile data is really on the eSIM (classic dual-SIM trap: signal shows the eSIM, data still routes via the home SIM).
- Toggle airplane mode for 10 seconds, or restart.
Symptom 4: Very slow speeds
- Rule out FUP throttling first: many "unlimited" plans cap daily high-speed data (commonly 1–3GB/day), then drop to 128Kbps–1Mbps. Check the FUP terms or ask support how much high-speed data you've used today.
- Switch networks manually: turn off automatic selection and try another local carrier — speeds vary wildly between networks.
- Move: indoors, basements and subways are physics, not bugs.
- Turn off your VPN and retest — some VPN routes halve your speed.
Symptom 5: Hotspot won't turn on / friends can't connect
- Check whether the plan allows tethering at all — some ban it outright; nothing fixes that.
- iPhone: Settings → Personal Hotspot → Allow Others to Join; if the option is greyed out, a restart usually brings it back.
- Android: make sure the APN type includes dun (set APN type to default,dun).
- Switch mobile data to the eSIM first, then enable hotspot.
Symptom 6: iPhone shows SOS
SOS means no carrier network at all. In order: confirm the eSIM line is enabled → data roaming is on → manual network selection → remove the physical SIM leaving only the eSIM → restart. Just landed? Give the phone 5–10 minutes to search — don't delete and reinstall in a panic.
When to stop DIY and contact the seller
- QR code says already used/expired — only the seller can reissue.
- APN, roaming and restarts all tried, still no data — ask the seller to check whether the plan is actually activated on their backend.
- Data vanished mysteriously — ask support for a usage breakdown.
Say it all in one message: phone model + OS version + exact symptom + error screenshots + EID (dial *#06# for the number) — it saves three or four back-and-forths.
FAQ
- Installed but no signal — most likely cause?
Nine times out of ten, data roaming is off on the eSIM. Turn roaming on, confirm data is switched to the eSIM, restart. - Signal but no internet?
Confirm data remains and the plan is activated; check the APN (get the exact value from the seller); toggle airplane mode or restart. - QR code expired?
Codes are mostly single-use — "already used" means asking the seller for a new one; re-scanning won't help. - Slow — am I throttled?
Check FUP first: many "unlimited" plans cap daily high-speed data. Otherwise try manual network switch, move location, turn off VPN. - Why won't hotspot work?
Confirm the plan allows tethering; check iPhone's "Allow Others to Join" or Android APN type dun. - Deleted the eSIM — recoverable?
Usually not; you'll need a new code from the seller. So don't delete the eSIM while troubleshooting — you'd lose the card without fixing the problem. - Can I test at home before the trip?
Some eSIMs catch a roaming signal at home for verification; no signal doesn't mean it's broken — it usually connects automatically after landing. Install before departure and troubleshoot with this guide; far steadier than installing on arrival.