Shield Fighter

A Dual Shield fighter is possible, but is restrictive and fiddly.

Dual Shielding

Beginning when you choose this archetype at 3rd level, Allows a the use  of two shields, one on each arm and receive the full AC bonus from both, this counts as engaging in Two-Weapon Fighting.

Character may make a bashing attack with the shields for 1d6 + Str + shield AC bludgeoning damage.

Shield Wall

Starting at 7th level, For any dexterity saving throw that allows a character to take half damage from area of effects, if successful, character takes no damage.

at level 18, this can be used for Strength and Constitution saving throws.

Spell Reflection

At 10th level, When you roll a 20 on the save or the caster rolls a 1 on the attack you reflect the spell back to caster.

at level 18 the range increase by one, (When you roll a 20-19 on the save or the caster rolls a 1-2 on the attack.

Vanguard

Starting at 15th level, As a bonus action if the character successfully strikes a target with the shield strike, you can take the dodge action, you can only do so an amount equal to your proficiency bonus.

While dodging this way unerring attacks will need to make an attack roll to hit.

Shield Charge

At 18th level, if the fighter moves at least 10 feet straight toward a target and then hits it with a shield bash attack on the same turn, the target takes an extra 9 (2d8) Bludgeoning. If the target is a creature, it must succeed on a DC {Str+Prof+Shield AC} Strength saving throw or be pushed up to 10 feet away and knocked prone. 

being pushed in to a surface would deal damage as if falling.