If you'll ever experience problems with connecting to I2P network, your Internet Service Provider may be blocking access to I2P bootstrap servers. It is not a big deal if you have access to GitHub.
Edit reseed section in your i2pd config file
i2pd.conf file like that:
[reseed] verify = true file = https://github.com/r4sas/i2pd-reseed/releases/download/1.0/i2pseeds.su3
or run binary with option:
./i2pd --verify true --reseed.file https://github.com/r4sas/i2pd-reseed/releases/download/1.0/i2pseeds.su3
and you will bootstrap to I2P network from GitHub.
Alternatively, simply download this file with web browser and reseed from local file:
./i2pd --verify true --reseed.file i2pseeds.su3