Unable to use I2P on Ubuntu 20.04 / 21.04

[Bitcoin]

Unable to use I2P on Ubuntu 20.04 / 21.04

I configured the I2P according to this answer on Ubuntu 20.04 and 21.10.

But I have been getting the following error when I try to connect to any I2P peer:

I2P: Error connecting to a5qsnv3maw77mlmmzlcglu6twje6ttctd3fhpbfwcbpmewx6fczq.b32.i2p:0: Receive timeout (received 0 bytes without terminator before that)

This error occurs for any peer, not just the above.

How can I find the reason for this error and fix it?

UPDATE: Adding information requested by Prayank.

$ sudo ufw status verbose
Status: inactive

$ ss -nlt
State                Recv-Q               Send-Q                               Local Address:Port                                Peer Address:Port               Process               
LISTEN               0                    128                                      127.0.0.1:7656                                     0.0.0.0:*       
...

UPDATE 2: I was able to reach the website git.idk.i2p using the steps described in http://geti2p.net/en/about/browser-config .

UPDATE 3: Results of executing the steps: https://github.com/vasild/bitcoin/pull/4

$ telnet 127.0.0.1 7656
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
HELLO VERSION MIN=3.1 MAX=3.1
HELLO REPLY RESULT=OK VERSION=3.1
SESSION CREATE STYLE=STREAM ID=mysession1 DESTINATION=TRANSIENT SIGNATURE_TYPE=7
<no-response>

According to the text, a response (SESSION STATUS RESULT=OK) was expected. This didn't happen. No response was received.

Result of the other test.

$ telnet 127.0.0.1 7656
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
HELLO VERSION MIN=3.1 MAX=3.1
HELLO REPLY RESULT=OK VERSION=3.1
NAMING LOOKUP NAME=git.idk.i2p
NAMING REPLY RESULT=OK NAME=ME VALUE=80...AAA==
STREAM CONNECT ID=mysession1 DESTINATION=80...AAA== SILENT=false
STREAM STATUS RESULT=CANT_REACH_PEER

Received CANT_REACH_PEER instead of STREAM STATUS RESULT=OK.

Source: Unable to use I2P on Ubuntu 20.04 / 21.04