Is SR an Ether Theory?
The answer is: YES.
Here's why:
1. SR and LET have the same math and thus the same predictions for all
experiments and observations.

2. LET is an ether theory and the math of LET is based on the assumptions
that the LET observer is in a state of absolute rest and that's why a LET
observer predicts all the clocks moving wrt him are running slow and all the
rods moving wrt him are contracted.

3. Similarly, an SR observer assumes that he is in a state of rest and all
the objects moving wrt him are doing the moving and thus all clocks moving
wrt him are running slow and all rods moving wrt him are contracted.

4. But SR also said that the speed of light is a universal constant in all
inertial frames. This seems to disagree with the ether concept. NOT so if we
define the speed of light as a constant math ratio in all inertial frames as
follows:
Light path length of ruler (299,792,458 m long physically)/the absolute time
(duration) content for a clock second co-moving with the ruler.

5. With the above definition for the speed of light the SR postulates can be
defined as follows:
(1). The laws of physics based on a clock second and a light-second to
measure length are the same for all observers in all inertial reference
frames.
(2). The speed of light in free space based on a clock second and a
light-second to measure length has the same mathematical ratio c in all
directions and all inertial frames.

The above new definition for the speed of light gives rise to a new theory
of relativity called Improved Relativity Theory (IRT). The postulates of IRT
are as follows:
1. The laws of physics based on a clock second and a light-second to measure
length are the same for all observers in all inertial reference frames.
2. The speed of light in free space based on a clock second and a
light-second to measure length has the same mathematical ratio c in all
directions and all inertial frames.
3. The laws of physics based on a defined absolute second and the physical
length of a measuring rod is different in different frames of reference.
4. The one-way speed of light in free space based on a defined absolute
second and the physical length of a measuring rod has a different
mathematical ratio for light speed in different inertial frames. The speed
of light based on a defined absolute second and the physical length of a
measuring rod is a maximum in the rest frame of the E-Matrix (ether).

IRT includes SRT as a subset. However, unlike SRT, the equations of IRT are
valid in all environments, including gravity. Also IRT is valid for use to
replace GRT in cosmology applications. IRT is described in a paper entitled
"Improved Relativity Theory" in the following website:
http://www.geocities.com/kn_seto/index.htm