Cant get less than 2 mae in W4 assignment

I am using the following architecture:

[code removed - moderator]

with the following compiler

[code removed - moderator]

I tried many other architectures and optimizers and cant get less than 2 mae.

For LSTM, consider increasing number of units as you go deeper in the network. Start with a much smaller network and see if things take shape.
Please see this link as well.