UI can't retrieve data (server side events broken?)

On the latest master (8fa94508), I have clean stork running, using rake docker_up.

I've observed a plethora of problems:

1. added agent-kea, which initially worked ok, but later (after couple mins) reported comm problem with the dhcpv4 and ca daemons ("There is observed issue in communication with the daemon.", see screenshot 1)
2. added agent-kea-ha1, agent-kea-ha2, they report losing communication. ha1 becomes unreachable, ha2 reports partner down (see screenshot 2)
3. the RPS and pool utilization is not updated anymore (clicking refresh buttons in the ui, pressing ctrl-r doesn't change a thing, see screenshot 3)
4. the daemons status is broken (shows all as grey no-entry sign, but when you hover your cursor over it, some say the communication is ok, see screenshot 4)

I'm reporting all of those in a single issue, because I believe most of them (maybe except the log viewer) can be explained with a problem with server side events. More on this in the first comment.

SCREENSHOT 1 (lost comm with dhcpv4 and ca running on agent-kea)

SCREENSHOT 2 (ha1 lost comm with its partner)

SCREENSHOT 3 (dashboard not updated)

SCREENSHOT 4 (broken app status update)