mjhjmtu

It is impossible to install Zabbix with apt-get install on my Debian 9.
I was following instructions on Zabbix page - I choose version 3.4 - Debian 9 - PostgreSQL but also 3.2, 3.0 LTS version or MySQL instead Postgres - no effect.
When I try to install Zabbix with command:

apt install zabbix-server-pgsql zabbix-frontend-php php-pgsql zabbix-agent

Then output looks like this (original output in polish - this is my translate):

(...)
incorrect checksum
 Hashes of expected file:
 SHA256: 2cd774 (...)
 MD5Sum: 2636bf (...)
 Filesize: 231550 [weak]
 Hashes of received file:
 SHA256: 9214bd (...)ap
 MD5Sum: e4c0b (...)
 Filesize: 2438 [weak]
last modification reported: Tue, 30 Jan 2018, 17:04
E: Cannot download some files, please try apt-get update or --fix-missing option

Of-course apt-get update or --fix-missing not resolved problem.
My sources.list is standard (Polish Debian repositories) but I also tried US or even Australian test servers.

I tried

rm -rf /var/lib/apt/lists/*

and apt-get clean, update, upgrade etc. Nothing helped. Problem is only with zabbix-server-pgsql or zabbix-server-mysql. Other packages installed correctly.
The same problem is with 3.2 and 3.0 LTS version.

EDIT

I used following instruction before apt install:

 wget http://repo.zabbix.com/zabbix/3.4/debian/pool/main/z/zabbix-release/zabbix-release_3.4-1+stretch_all.deb
 dpkg -i zabbix-release_3.4-1+stretch_all.deb
 apt update 

Instructions from zabbix.com/download page.
Moreover, I tried to install Zabbix on my test Debian 8 on VirtualBox and there is a problem too, but only information is after apt install is -

cannot download (...) libsnmp30 (...) - wrong size

SOLVED -
Fortigate firewall blocked libsnmp30 package - even if I want download it from web browser from Debian repositories. I downloaded it by proxy, install package by dpkg and it works.

Solved! There was a problem with firewall / router which blocked the libsnmp30 package. I downloaded it manually and installed with dpkg.