Home Media Center help needed.

I could really use some help from you more experienced folks when it comes to home media setups. I have attempted to set up a home media system at my place but I'm sure my setup is not the proper way for setup. I say that because the movies are at best times pixelated and at worst times constantly stopping and buffering.

Here is what I have. Please bare with me as not all my equipment is Apple equipment. I am willing to replace the server unit with a Mac Mini and replace my database storage with a Time Capsule or the like if needed but that all depends on what input I get from you fine folks.

Server Unit with Plex Manager:
HP Desktop

Storage for movies/videos connected to Desktop:
USB WD 2TB
USB WD 1TB

WiFi via AT&T UVerse hub

Clients:
Sony TV via Roku box with Plex app (living room) (This TV has built-in wifi and Ethernet)
Sony TV via Roku box with Plex app (bedroom)
Apple 27" iMac with Plex app (Office)
Apple MacBook with Plex app (floater)
(2) Android Tablets with Plex app (floaters)
(2) Apple iPhones with Plex app (floaters)

I'm thinking the proper way should be to have a MacMini (or similar) with Plex Manager installed and USB drives attached to it sitting next to the living room tv. Connect Mac Mini with Ethernet directly to the AT&T hub and connect the living room Sony TV to the AT&T hub via Ethernet. Am I right? Like I said, I am a total newb at this. Any help is appreciated.

As for storage, would replacing the (2) USB drives with a Time Capsule buy me anything?

My goal is to stop the pixelating and buffering and have the movies play seamlessly. Any ideas?

Thanks,

There are several things here to consider:
1. Does the server have enough power (CPU and RAM) to serve (potentially transcode) video to all those clients? What CPU and RAM is in there?
2. Your network has to shift all this data about. Ethernet cable everything you can. Use ethernet-over-power to get to cable inaccessible areas.
3. Make sure you're wi-fi signal is strong. Where needed. Use repeaters if required.
4. File formats. If your videos are in file formats that can't be natively played by the receiving device, Plex on the server will have to transcode the file on-the-fly. This takes processor grunt and introduces a time factor - i.e. buffering. Consider converting your files to a common file format like MP4 to minimise this kind of conversion.

I see no value in getting a Mac Mini or TC over the kit you've listed (providing the Server is powerful enough)

Thanks for the response Mrplow.

1. I usually only have one client in use at a time. It's usually the living room tv. The others have apps installed in the event the urge arises. But, the living room tv is the primary client. Server unit specs are: Intel Pentium 2.9 | Intel HD 2500 | 1TB HDD | 6GB RAM

2. Sounds like you're saying moving my server unit out of the office (which is on the other side of the wall from the tv) and have it sit next to the tv (connected via Ethernet) is the best way to go. If so, this is what I meant by willing to buy a MacMini which would have a smaller footprint than my HP Desktop has.

3. Not sure how strong the signal is. Like I said, my office currently sits next door to the living room. Router is next to the tv. I would say currently about 10 ft distance from router to the server unit and going through one wall.

4. Files are currently all mkv files.

Thanks again.

1 & 4 MKV is the biggest ask of a transcoding setup. They can also have a wide variety content being simply containers. They are often high bitrate. I.e. worst case scenario! and most likely to highlight issues in your setup

2. You can do that or you can put a cable through the wall or use ethernet over power adapters

3. use NetSpot on your macbook and you can 'map' your wireless dead spots

The first thing to do is temporarily connect the server, router and TV roku by ethernet cable. Copy a particularly troublesome MKV onto the local drive of the server and try that.
This is the best case scenario for the kit you have (i.e. using 10/100 ethernet and no external drives)
If this works, great. The server is up to the transcoding job. Now try the same file but from one of the external drives. If it works, great, if not the server isn't coping with doing a USB data transfer and the transcoding job.

Once you have all this troubleshooting data you'll be in a much better position to see the weak spots and then, go on to change your setup/replace kit to provide a robust solution.

Excellent suggestions MrPlow. I'll try doing that experiment. I had not thought about the simultaneous USB read and transcode workload.

Thanks again.