Tethering/ Hotspot broken for (secondary) eSIM, UDP packets get no response
- /e/OS version: 3.1.3
- Device model(s): FP6 (Murena edition)
The problem
When sharing my phone's internet connection via a mobile WLAN hotspot, it is not properly usable by the connected devices. A network analysis reveals that DNS resolution fails due to UDP packets not receiving an answer. Direct (IPv4) TCP and ICMP echo connections work fine and get a proper response.
This issue only appeared with my (secondary) travel eSIM. Provider: 1global Tethering works just fine with my physical main SIM. Provider: Vodafone
I also contacted the affected mobile provider in parallel to figure out potential issues on their side. Will update once a response is available.
Steps to reproduce
- get a data-only eSIM. I used https://www.freenet-mobilfunk.de/travel/
- Enable it, book a data packet on it.
- Set the eSIM as the main mobile data provider
- Enable the mobile tethering WLAN hotspot
- connect an external device (e.g. laptop) to the hotspot
- Encounter that web browsing and most further connections are broken due to failing DNS resolution. For reproducer commands, see Technical Details below.
I did not check whether this requires both SIMs to be enabled at the same time, I'm just describing the setup I encountered the issue in.
Technical details
Paste any relevant logs (adb logcat) in the codeblock below if you have any
Additionally, I can provide a Wireshark packet capture of the failing DNS resolutions on request.
- affected OS of connected devices: Linux (NixOS with Network Manager), macOS
- used DNS resolvers: 1.1.1.2, 86.54.11.1
- ICMP:
- ICMP echo requests (
ping) to the DNS resolver IP get successful responses - traceroutes with
mtrsuccessfully show the full path to the destination IP$ sudo mtr -4 --report -c 5 86.54.11.1 Start: 2025-09-12T09:06:19+0200 HOST: MacBook Pro Loss% Snt Last Avg Best Wrst StDev 1.|-- 192.168.56.186 0.0% 5 102.6 74.6 8.5 228.3 94.3 2.|-- 10.31.126.18 40.0% 5 353.9 280.3 178.7 353.9 90.9 3.|-- 10.31.126.17 0.0% 5 258.0 130.6 41.2 258.0 94.4 4.|-- 10.31.255.201 0.0% 5 166.6 141.2 83.6 209.2 51.2 5.|-- ??? 100.0 5 0.0 0.0 0.0 0.0 0.0 6.|-- 192.168.210.86 0.0% 5 81.4 108.4 62.8 212.9 61.3 7.|-- 213.251.19.141 0.0% 5 75.5 76.8 56.2 107.8 18.9 8.|-- 213.200.117.170 0.0% 5 137.1 273.3 87.3 832.1 314.9 9.|-- 154.14.43.114 0.0% 5 44.2 251.6 44.2 736.1 287.6 10.|-- 79.127.192.137 0.0% 5 73.9 214.7 73.9 641.0 243.8 11.|-- 86.54.11.1 0.0% 5 144.2 192.5 69.2 545.1 198.9
- ICMP echo requests (
- UDP, DNS:
- trying to resolve a domain, e.g.
dig @86.54.11.1 e.foundationtimes out$ dig @86.54.11.1 e.foundation ; <<>> DiG 9.10.6 <<>> @86.54.11.1 e.foundation ; (1 server found) ;; global options: +cmd ;; connection timed out; no servers could be reached - Wireshark packet capture reveals that the DNS query packets never receive a response
-
mtr -utraceroutes show a few hops, but never reache the final destination$ sudo mtr -4 -u --report -e -c 5 86.54.11.1 Start: 2025-09-12T09:05:22+0200 HOST: MacBook Pro Loss% Snt Last Avg Best Wrst StDev 1.|-- 192.168.56.186 0.0% 5 12.0 16.4 7.3 36.8 11.7 2.|-- 10.31.126.18 0.0% 5 48.4 59.3 45.3 75.1 12.4 10.31.126.22 3.|-- 10.31.126.21 0.0% 5 46.6 58.1 39.2 109.2 29.2 10.31.126.17 4.|-- 10.31.255.201 20.0% 5 63.7 77.9 63.7 93.0 15.0 10.31.255.205 5.|-- ??? 100.0 5 0.0 0.0 0.0 0.0 0.0 6.|-- 192.168.210.86 0.0% 5 98.0 99.7 47.7 167.7 46.4 7.|-- 213.251.19.141 0.0% 5 52.6 56.5 38.0 77.1 19.3 8.|-- 213.200.117.170 20.0% 5 79.4 75.7 65.3 84.7 8.3 9.|-- 154.14.43.114 0.0% 5 77.1 54.7 38.5 77.1 16.8 10.|-- 79.127.192.141 0.0% 5 77.6 65.7 50.9 77.6 10.4 79.127.192.137 11.|-- ??? 100.0 5 0.0 0.0 0.0 0.0 0.0
- trying to resolve a domain, e.g.
- TCP:
- direct connections towards a known IPv4 address work fine.
- example: showing the SMTP server banner by connecting to an SMTP MTA server via netcat:
nc <ip address of known mail server> 587prints the EHLO banner$ nc -v 148.251.55.246 587 Connection to 148.251.55.246 port 587 [tcp/submission] succeeded! 220 mail.orlives.de ESMTP 500 5.5.2 Error: bad syntax