accessing zabbix frontend kills it all

[kisiel]

Dear all, please help

I am fairly new to zabbix. I monitor my small network (less than 10 machines).
My Zabbix server is a small VPS with 2GB ram running Ubuntu 16.04
I believe I am running zabbix 3.2

I don't know what happened, but my zabbix web frontend started hanging the whole server.
Typical scenario:
I am logged in via ssh to my zabbix server
then I try to access the web frontend (https). Browser logs me in automatically. I can see the page loading and then it hangs.
My ssh session gets disconnected.
Zabbix server starts sending emails that it lost connection to all the agents

I have to close the webpage or wait for the timeout. Then give it a moment, and ssh starts working again, and zabbix sends notifications that it can connect to the agents.

The only change that comes to my mind was to replace Linux template with the active template. I am aware that my server is rather tiny, Did I manage to overload it? How can I fix it?

Thanks,
Marcin

[kisiel]

To be precise:
my zabbix server version is 3.4.12
running on Ubuntu 16.04.5 LTS
zabbix log /var/log/zabbix-server/zabbix_server.log does not indicate anything special except "network error" and "host unavailable". I assume those messages are related to server losing connectivity.
anyone? my zabbix is effectively dead.

one thing I noticed is that mysql consumes most of what little memory my VPS has. Could this be the problem? but I am not sure how would it cause SSH to drop
Marcin