network diagram and config
/export hide-sensitive file=anynameyouwish

The network diagram will fully explain the connectivity between component of the network and if annotated with Ip addresses will explain the subnet relationships.
The config is something you can create from the terminal part of winbox,
It then puts the file into the FILES selection in winbox and then you can download it, open it with notepad++
then paste in here.

Just be sure to use the CODE tags on the same line above as B and Underline (its the black square with white square brackets)/

Plex is on a docker as host, with port forwarding set up to the server, It plays perfectly away from home.
When I try and use plex app on my my iPhone and appletv I get limited connection and nothing plays.
I have read that it could be dnsmasq but I have no idea what that is or how to change it, looking for some help

Plex is on a docker as host, with port forwarding set up to the server, It plays perfectly away from home.
When I try and use plex app on my my iPhone and appletv I get limited connection and nothing plays.
I have read that it could be dnsmasq but I have no idea what that is or how to change it, looking for some help

Plex app on your phone ? And your are connected on WIFI on your LOCAL LAN ? What is the purpose of the iphone ? If the Plexapp is on AppleTV, and AppleTV connected to a TV-set, why not control the Plex-app on AppleTV with the remote while you are at home ?

Anyway, it might be related to "hairpin nat" ? On your iPhone / Plex-app, what "server" information is filled in ? Your public IP ? Some DNS-name ?

You probably try to call the same hostname (eg. plexserver.mydomain.something) from inside your home local network ??

Plex is on a docker as host, with port forwarding set up to the server, It plays perfectly away from home.
When I try and use plex app on my my iPhone and appletv I get limited connection and nothing plays.
I have read that it could be dnsmasq but I have no idea what that is or how to change it, looking for some help
Appletv has its own app and so does iPhone when you connect you join to app.plex.tv not your local server if I could just put in the ipaddress it would be easier for me I dont have a domain setup on it I could I have a domain for other things but not plex

I'm sure you can add your local IP/hostname of any server you run locally. I run Plex for years on Tizen (Samsung TV) , Android & iPhone and each of these apps you can always in the advanced settings override and put something else.
On your LOCAL Plex server, on "Settings" > "Remote Access" does it say fully "OK" ? (green) and tells you the Plex is accessible from the outside ? Does it indicate something like "relaying" or "limited bandwidth" or someting ???
That means your local content is streaming via de Plex cloud-servers and bandwidth is limited (not optimal)

Under "Settings" -> "Network" , what is selected with "Enable local network discovery (GDM) ? Again, depending docker-setup this might fail too as docker actually uses "NAT" by default and uses an internal 172.x.x.x IP for a docker-container and exposes some ports (that you make in your port-mapping config) to the local LAN.

So the things is, depending on how you configured your container (docker) on the Network side, the IP-address of the Plex might differ from your local LAN. Are you using "bridging" on the docker side, so "use the host network-settings" of some sort ?

Bottom line : again 10 possible causes, and (probably) nothing "Mikrotik" related. IF your remote-access works OK and you can remotely view content from your HOME-server, then at least your Mikrotik seems to work.