Да, похоже на блокировку, вероятно, по какому-то особому признаку. Предполагаю, что по ответу сервера, т.к. изменение домена и параметров в ClientHello не помогает.
openssl s_client -starttls xmpp-server -host xmpp.quicksy.im -port 5269 -xmpphost quicksy.im -servername quicksy.im </dev/null &>/dev/null && echo ok || echo fail
| Node | ISP | AS | City | test 9 Apr | test 10 Apr | test 21 Apr |
|---|---|---|---|---|---|---|
| RU-001 | ТТК | AS8427 | Magnitogorsk | ok | ok | ok |
| RU-002 | Интерсвязь is74 | AS8369 | Yemanzhelinsk | ok | ok | ok |
| RU-003 | МТС | AS28832 | Chelyabinsk | fail | fail | fail |
| RU-004 | МГТС | AS25513 | Moscow | ok | ok | ok |
| RU-005 | Dom.ru | AS49048 | Tver | ok | ok | ok |
| RU-006 | Dom.ru | AS50544 | Krasnoyarsk | fail | fail | fail |
| RU-009 | Линклайн | AS44041 | Moscow | ok | ok | fail |
| RU-010 | МГТС | AS25513 | Moscow | ok | ok | ok |
| RU-011 | ENEVA/OBIT | AS8492 | Saint Petersburg | fail | ok | fail |
| RU-012 | Beeline/Corbina | AS8402 | Tula | ok | ok | fail |
| RU-013 | Dom.ru | AS50543 | Saratov | fail | fail | fail |
| RU-014 | Rostelecom | AS12389 | Orenburg | ok | ok | ok |
| RU-018 | Evpanet | AS43936 | Krimea | ok | ok | ok |
| RU-020 | PJSC MegaFon | AS31205 | Khakasiya | ok | ok | ok |
| RU-021 | ER-Telecom Holding | AS56981 | Tomsk | ok | ok | ok |
| RU-022 | Sibirskie Seti | AS40995 | Novokuznetsk | ok | ok | ok |
| RU-023 | Rostelecom | AS12389 | Perm region | ok | ok | ok |
| RU-024 | Beeline | AS34038 | Tyumen | ok | ok | ok |
| RU-025 | Rostelecom | AS12389 | Kemerovo | ok | ok | ok |
| RU-026 | Rostelecom | AS12389 | Kemerovo | fail | fail | fail |
| RU-027 | Sibirskie Seti | AS47433 | Kemerovo | ok | ok | ok |
| RU-028 | Beeline | AS3216 | Kemerovo | ok | ok | fail |
| RU-029 | Rostelecom Mobile | AS12389 | Kemerovo (Spb SIM) | ok | ok | ok |
| RU-031 | Beeline | AS42110 | Sochi | ok | ok | ok |
| RU-032 | Sibirskie Seti Ltd. | AS34757 | Novosibirsk | fail | fail | fail |
| RU-033 | Yota | AS31213 | Saint Petersburg | ok | ok | ok |
| RU-035 | UBS (ubsnet.ru) | AS50042 | Sevastopol | ok | ok | ok |