explain says:

+------+--------------------+------------------+----------------+---------------------------------+-----------------+---------+------+----------+--------------------------+
| id   | select_type        | table            | type           | possible_keys                   | key             | key_len | ref  | rows     | Extra                    |
+------+--------------------+------------------+----------------+---------------------------------+-----------------+---------+------+----------+--------------------------+
|    1 | PRIMARY            | item-uri         | range          | PRIMARY                         | PRIMARY         | 4       | NULL | 12510257 | Using where; Using index |
|   19 | MATERIALIZED       | mail             | range          | thr-parent-id                   | thr-parent-id   | 5       | NULL | 1363     | Using where; Using index |
|   18 | MATERIALIZED       | mail             | range          | parent-uri-id                   | parent-uri-id   | 5       | NULL | 1363     | Using where; Using index |
|   17 | MATERIALIZED       | post-delivery    | index          | inbox-id_created                | uid             | 4       | NULL | 1        | Using index              |
|   16 | MATERIALIZED       | post-delivery    | index          | PRIMARY                         | uid             | 4       | NULL | 1        | Using index              |
|   15 | MATERIALIZED       | inbox-status     | range          | uri-id                          | uri-id          | 5       | NULL | 549390   | Using where; Using index |
|   14 | MATERIALIZED       | diaspora-contact | index          | PRIMARY                         | gsid            | 5       | NULL | 18742    | Using index              |
|   13 | MATERIALIZED       | apcontact        | range          | uri-id                          | uri-id          | 5       | NULL | 315107   | Using where; Using index |
|   12 | MATERIALIZED       | contact          | range          | uri-id                          | uri-id          | 5       | NULL | 358020   | Using where; Using index |
|   11 | MATERIALIZED       | user-contact     | range          | uri-id_uid                      | uri-id_uid      | 5       | NULL | 6463     | Using where; Using index |
|   10 | MATERIALIZED       | event            | range          | uri-id                          | uri-id          | 5       | NULL | 483      | Using where; Using index |
|    9 | MATERIALIZED       | mail             | range          | uri-id                          | uri-id          | 5       | NULL | 1363     | Using where; Using index |
|    8 | DEPENDENT SUBQUERY | post-thread      | index_subquery | conversation-id                 | conversation-id | 5       | func | 1        | Using index; Using where |
|    7 | MATERIALIZED       | post-thread      | range          | context-id                      | context-id      | 5       | NULL | 18624    | Using where; Using index |
|    6 | MATERIALIZED       | post-user        | range          | replies-id                      | replies-id      | 5       | NULL | 9678376  | Using where; Using index |
|    5 | MATERIALIZED       | post-user        | range          | external-id                     | external-id     | 5       | NULL | 17342    | Using where; Using index |
|    4 | DEPENDENT SUBQUERY | post-user        | index_subquery | thr-parent-id                   | thr-parent-id   | 5       | func | 2        | Using index; Using where |
|    3 | DEPENDENT SUBQUERY | post-user        | index_subquery | parent-uri-id,parent-uri-id_uid | parent-uri-id   | 5       | func | 4        | Using index; Using where |
|    2 | DEPENDENT SUBQUERY | post-user        | index_subquery | uri-id                          | uri-id          | 4       | func | 1        | Using index              |
+------+--------------------+------------------+----------------+---------------------------------+-----------------+---------+------+----------+--------------------------+

No connection to Hubzilla channels possible.

I host two Hubzilla hubs and one Friendica instance. The hub ‘hub.hubzilla.hu’ and the Friendica instance ‘barat.fedi-verse.hu’ are running on a VPS under YunoHost. The second hub ‘klacker.org’ runs on another VPS where it is installed manually.

It is not possible to create connections between my Friendica channel and a Hubzilla channel that is on one of my two hubs. Connecting (with handle or also with the Proful URL) from Friendica leads to ‘504 Gateway Time-out’ after some time. If I check the channels in the admin area ‘Check address’, the error ‘504’ appears even after a long wait.

If I establish a connection to my Friendica channel from one of the Hubzilla channels, the connection is displayed as established in Hubzilla. In Friendica, however, the connection does not appear under ‘Contacts’. I also do not receive a connection request from Friendica and the channel does not appear under ‘Pending’.

With my channels on the two hubs, I have functioning connections to channels on other Friendica instances without any problems. There are also no problems with connections to other Fediverse services.

I also have working connections from my Friendica channel to Hubzilla channels on hubs other than my own, which work fine.

As a test, I also made connections from another Friendica account (at anonsys) to channels on my two hubs. This also worked without any problems.

Connections from the other (third-party) Friendica channel to my own Friendica channel can also be established without any problems.

Address-Probe attempts lead to error messages in the nginx log:

2024/11/10 00:09:04 [error] 3869222#3869222: *11133498 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 5.204.231.9, server: barat.fedi-verse.hu, request: "GET /probe?addr=pepecyb%40hub.hubzilla.hu HTTP/2.0", upstream: "fastcgi://unix:/var/run/php/php8.2-fpm-friendica.sock", host: "barat.fedi-verse.hu", referrer: "https://barat.fedi-verse.hu/probe"

2024/11/10 09:57:09 [error] 3869222#3869222: *11201928 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 5.204.231.9, server: barat.fedi-verse.hu, request: "GET /probe?addr=hvetinari%40klacker.org HTTP/2.0", upstream: "fastcgi://unix:/var/run/php/php8.2-fpm-friendica.sock", host: "barat.fedi-verse.hu", referrer: "https://barat.fedi-verse.hu/probe"

I am desperate because I have no idea what the reason for this could be and how I can eliminate the malfunction. Does anyone have any ideas?