Update network usage info

Suggestion, how we could document usage of floating networks. If agreed on, I can prepare CI job, that will go through floating IPs and gateways allocated to group projects and will release IPs belonging to default network (which should be used only by personal projects).

faq/README.md

@@ -4,7 +4,7 @@
 Follow instructions for registering in [MetaCentrum Cloud](/register/README.md).
 
 ## How do I migrate from legacy platforms?
-Follow instructions for [migrating from CESMET-MetaCloud or OStack ICS MUNI](/migrate/README.md).
+Follow instructions for [migrating from CESNET-MetaCloud or OStack ICS MUNI](/migrate/README.md).
 
 ## Where do I report a problem?
 First, try searching the documentation for an answer to your problem. If that does not yield results, open a
@@ -12,3 +12,15 @@ ticket with [cloud@metacentrum.cz](mailto:cloud@metacentrum.cz). When contacting
 include your *username* (upper right corner of the web interface) and *domain* with
 active *project* (upper left corner of the web interface) as well as a description of
 your problem and/or an error message if available.
+
+## What networks I can use to access my instances?
+Personal projects can allocate floating IPs from *public-muni-147-251-124* and *private-muni-10-16-116*.
+Group projects can currently allocate floating IPs from *public-cesnet-78-128-251* and *private-muni-10-16-116*.
+IP addresses from *public-muni-147-251-124* allocated by users to group projects are released daily, so we encourage
+using only *public-cesnet-78-128-251* and *private-muni-10-16-116* for group projects.
+
+## Issues with network stability in Docker
+OpenStack instances use 1442 bytes MTU (maximum transmission unit) instead of standard 1500 bytes MTU. Instance itself is
+able to setup correct MTU with its counterpart via Path MTU Discovery. Docker needs MTU setup explicitly. Refer documentation for setting up
+1442 MTU in [Docker](https://docs.docker.com/v17.09/engine/userguide/networking/default_network/custom-docker0/) or
+[Kubernetes](https://docs.projectcalico.org/v3.5/usage/configuration/mtu).