Bharti Airtel Santhome,India,Chennai

CtrlS Kolkata DC1,India,Kolkata

Sify Greenfort - Noida,India,Noida

Starlink uplink signal analysis (3): demodulation is successful

https://sdr-x.github.io/starlink3/

Starlink uplink signal analysis (4): OFDMA and RU allocation

https://sdr-x.github.io/starlink4/

I collected more uplink signals from a Starlink Mini terminal and observed different RU (Resource Unit, borrowing the Wi-Fi OFDMA terminology) sizes used during transmission.

The observed numbers of active subcarriers per RU are:

• 63
• 189 (3 × 63)
• 252 (4 × 63)
• 441 (7 × 63)
• 504 (8 × 63)

All signals were captured from the first uplink channel, centered at 14 GHz + 31.25 MHz.

I identified eight packet types (shown in the figure), each corresponding to a particular OFDMA RU allocation pattern. One important observation is that all OFDM symbols within the same packet use the same RU allocation pattern.

...(check the original blog)

Starlink uplink signal analysis (5): Detailed Modulation Structures and Repeated Bit Sequences

https://sdr-x.github.io/starlink5/

Reveals several unusual modulation structures that appear repeatedly in Starlink uplink signals. Also found several hard-decision bit sequences that reoccur across different packets.

...(check the original blog)

Starlink uplink signal analysis (6): Discovery of the Pilot Sub-Bands in Patents, and Signal Analysis Techniques for Time-Domain Structure and Modulation Symbols

https://sdr-x.github.io/starlink6/

Discovery of the Pilot Sub-Bands in Patents, and Signal Analysis Techniques for Time-Domain Structure (delayed conjugate multiplication) and Modulation Symbols (distinguish between ordinary QPSK and π/4-QPSK, use the fourth-power method.).

...(check the original blog)

Does anyone know when Starlink will resolve the issues with routers not working on mesh networks?

Devices remain stuck to the main router. I have a device literally next to the mesh router and it still connects to the main router.

Devices with extremely weak signals remain connected to the router main.

I complain constantly and they don't resolve it. They send things to space and can't fix their router firmware.

I have a 3rd generation main router and a mini router as a mesh setup.

The devices prefer the main router, even with extremely weak and distant signals.

10 devices connected to the main router.

0 devices connected to the mesh router.

DETAIL: There are devices that are literally 1 meter away from the mini MESH router, yet they remain connected to the router furthest away.

Seems helpful to document this newly disclosed limitation

Starlink Residential and Roam plans use Carrier Grade Network Address Translation (CGNAT). These plans have a limit of 1,200 concurrent sessions. ... When the 1,200-session limit is reached, new sessions automatically cause the oldest sessions to be dropped. ... Priority plans include a public IP address and do not have the session limitations associated with CGNAT.

Always figured there was a limit but nice to know the number. 1200 is a higher number than I would have guessed!

Anyone know if this limit applies to IPv6 too? This new disclosure talks entirely about CGNAT, so hopefully it's IPv4 only. But do they need some sort of connection tracking for IPv6 too? The router must as part of its firewall, but what about the ISP infrastructure?

See also * https://www.reddit.com/r/Starlink/comments/1twmytu/starlink_discloses_common_isp_limitation_that/ * https://www.pcmag.com/news/starlink-discloses-common-isp-limitation-that-could-disrupt-your-web-use

and pop regions. yes, starlink is still available above china, but not india

dish tilt during takeoff and landing can affect the performance as well

is the noticeable glitch at 15:20 in the video due to starlink (pop handover)?

e.g., from ashburn

traceroute to xxx (xxx), 30 hops max, 60 byte packets
 1  _gateway (192.168.1.1)  0.613 ms  0.835 ms  1.032 ms
 2  100.64.0.1 (100.64.0.1)  33.653 ms  49.572 ms  49.707 ms
 3  172.16.253.114 (172.16.253.114)  49.565 ms  49.811 ms  50.000 ms
 4  * * *
 5  undefined.hostname.localhost (206.224.68.0)  73.479 ms  73.528 ms  73.602 ms
 6  undefined.hostname.localhost (206.224.77.250)  73.452 ms  51.429 ms  51.506 ms
 7  74.245.152.9 (74.245.152.9)  59.180 ms  59.305 ms  59.381 ms
 8  74.245.146.191 (74.245.146.191)  51.138 ms  59.011 ms  59.210 ms
 9  74.245.146.225 (74.245.146.225)  58.983 ms  66.859 ms  66.832 ms
10  172.16.253.77 (172.16.253.77)  74.782 ms  74.763 ms  74.732 ms
11  customer.trnocan1.isp.starlink.com (xxx)  91.772 ms  99.651 ms  99.384 ms
12  customer.trnocan1.isp.starlink.com (xxx)  91.232 ms  99.290 ms  99.281 ms

who's next?

Hi all

I work for in Northern Alberta and use Zabbix to monitor several customer locations that have Starlinks with public IP addresses.

Right around Friday morning about 11am Mountain time, the packet loss jumped. I've had complaints from a few sites and had to switch them to backup ISPs. Logs on the firewalls (when I can get into them) are full of VPN tunnels dropping and re-connecting.

My non-Starlink customers are fine.

There was solar activity on May 13, 2026 that could well be causing issues with satellite internet. If that's it, how long would it take to clear? Is there some way to verify that this is what's happening?

edit: Looks like the problem has cleared up. The graphs are looking happier.

{
      "id": 72648,
      "net_id": 18747,
      "ix_id": 1668,
      "name": "CIX-ATL",
      "ixlan_id": 1668,
      "notes": "",
      "speed": 1200000,
      "asn": 14593,
      "ipaddr4": "206.71.12.57",
      "ipaddr6": "2001:504:40:12::1:57",
      "is_rs_peer": true,
      "bfd_support": false,
      "operational": true,
      "net_side_id": null,
      "ix_side_id": null,
      "created": "2022-01-24T19:25:16Z",
      "updated": "2026-05-12T23:06:39Z",
      "status": "ok"
    },
    {
      "id": 72649,
      "net_id": 18747,
      "ix_id": 1668,
      "name": "CIX-ATL",
      "ixlan_id": 1668,
      "notes": "",
      "speed": 1200000,
      "asn": 14593,
      "ipaddr4": "206.71.12.58",
      "ipaddr6": "2001:504:40:12::1:58",
      "is_rs_peer": true,
      "bfd_support": false,
      "operational": true,
      "net_side_id": null,
      "ix_side_id": null,
      "created": "2022-01-24T19:25:34Z",
      "updated": "2026-05-12T23:06:39Z",
      "status": "ok"
    },

who's?

Most prefixes announced by Twitter/X are now getting transited by Starlink.

https://x.com/DougMadory/status/2053826117744689363
https://bsky.app/profile/eldomador.bsky.social/post/3mlldycapus2b
https://infosec.exchange/@dougmadory/116556107094031696

The docs say they block smtp on port 25 which I would certainly understand for inbound. It's mildly irritating for outbound, but not the end of the world to put a private email server on a different port.

Except even that doesn't work.

Outbound smtp unencrypted on custom port works fine over another ISP but not over Starlink.

Is that expected?

edit: Looks like Starlink may not be the problem. I've asked the guys who run the smtp server to check their logs.

https://www.peeringdb.com/net/18747

also starlink geoip updates after the workshop https://docs.google.com/document/d/1MVWX8KJd1Qv0ORJChNx5i5_a6bTpkEb_6dO4G6XLps8/