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going mad with this. Setting up OpenVPN but one mobile phone gives me trouble. I tried to boil it down to this

Situation: I have a simple port 80 open on my router (OpenWRT) and forwarded to server in our lan serving simple static html page.

What does not work:

  • accessing it by http://xxx.xxx.xxx.xxx:80 (where xxx... is public IP of our router) from mobile phone X using mobile data outside of our lan.

what does work:

  • same phone but using wifi on the same lan (obviosely)
  • same phone using mobile data through VPN tunnel like Tunnelbear
  • same phone with different sim card (different isp)
  • same phone with different sim card (same isp)
  • same phone with dual sim cards both from the same isp (problem one doesnt work, other one works)
  • any laptop outside our lan I tried

Few more about what does NOT work....

  • transferred sim card from problematic mobile X to another phone Y that was working ok earlier .... now phone Y does not work either
  • changing public IP by going to airplane mode did not help

So, Id say its down to a single sim card! But how. Any other web or service works. Why this one not?

All I managed to check is some tcpdump on my router. Used tcpdump -i wwan0 port 80

Test 1 with working phone accessing URL mentioned above:

00:10:38.691243 IP 46.188.XXX.XXX.7334 > m77-216-XXX-XXX.cust.tele2.hr.80: Flags [.], ack 1, win 445, options [nop,nop,TS val 569073732 ecr 3787866537], length 0
00:10:38.757385 IP 46.188.XXX.XXX.7332 > m77-216-XXX-XXX.cust.tele2.hr.80: Flags [.], ack 810, win 457, options [nop,nop,TS val 569073800 ecr 3787866599], length 0
00:10:38.761025 IP 46.188.XXX.XXX.7332 > m77-216-XXX-XXX.cust.tele2.hr.80: Flags [.], ack 811, win 457, options [nop,nop,TS val 569073802 ecr 3787866600], length 0

Test 2 with non-working phone accessing URL mentioned above:

00:05:03.848492 IP m77-216-XXX-XXX.cust.tele2.hr.80 > 10.11.XXX.XXX.40184: Flags [S.], seq 1914262670, ack 3490008704, win 43440, options [mss 1460,sackOK,TS val 2255656298 ecr 1723147089,nop,wscale 9], length 0
00:05:05.723687 IP 10.11.XXX.XXX.40182 > m77-216-XXX-XXX.cust.tele2.hr.80: Flags [S], seq 879034002, win 65535, options [mss 1318,sackOK,TS val 1723154027 ecr 0,nop,wscale 8], length 0
00:05:05.724407 IP m77-216-XXX-XXX.cust.tele2.hr.80 > 10.11.XXX.XXX.40182: Flags [S.], seq 1268311359, ack 879034003, win 43440, options [mss 1460,sackOK,TS val 2255658174 ecr 1723146928,nop,wscale 9], length 0

... Is this a problem? Non working phone uses 10.11.XXX.XXX which is private IP of my phone (found it in settings -> about phone -> status -> ip address). That IP is of course not accessible from my router. Succeeding mobile phone used 46.188.XXX.XXX which is proper public IP.

Mirko Vukušić
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  • How is this anything more then the one ISP is using NAT on 10.11.x.x which us not routed thus return connection never get back to it? – davidgo Feb 08 '20 at 06:50
  • But why is then another sim card of the same isp working? We have contract with 7 cards with the same isp. I tested 3. Only one doesnt work. – Mirko Vukušić Feb 08 '20 at 09:16
  • Different plans / APN's set for SIM cards maybe. BTW/you should update your question which says SIM cards were from different ISPs (and problem followed SIM). – davidgo Feb 08 '20 at 09:54
  • i updated a Q a bit, added few more tests... different cards from same provider and also actually tried 2 cards inside dual sim phone (Samsung s10) where one works and another one doesn't. I compared APN settings one by one. I'll do it one by one again. – Mirko Vukušić Feb 08 '20 at 13:47
  • Speak to your SIM provider. – davidgo Feb 08 '20 at 18:28

0 Answers0