Advice for new DM with struggling players(balancing issues)

I´m curious: Has it been like that from the beginning or has it switched around at some level ?

I´m pretty new as a DM myself and I´m currently struggling with quite the opposite. I had my group of 4 (fighter, paladin, rogue, sorcerer) fight CR3 enemies at lvl 3 (for example an Owlbear and a Grell) and they barely were any challenge. Most of them died in the second round of combat and they just landed one or two hits on the players.

We play 5.5, so that might be a factor, but we don´t use the weapon masteries. In addition, I always use the maximum HP for all of the monsters instead of their average as shown in the monster manual. And the players barely have any magic weapons.

Last session, the players leveled up to 4, and fought a CR5 monster (a revenant) with three ice mephits (CR1/2) and while it at least took longer than 2 rounds, it still wasn´t really a challenge.

Quote from Eugel >>

I´m curious: Has it been like that from the beginning or has it switched around at some level ?

I´m pretty new as a DM myself and I´m currently struggling with quite the opposite. I had my group of 4 (fighter, paladin, rogue, sorcerer) fight CR3 enemies at lvl 3 (for example an Owlbear and a Grell) and they barely were any challenge. Most of them died in the second round of combat and they just landed one or two hits on the players.

We play 5.5, so that might be a factor, but we don´t use the weapon masteries. In addition, I always use the maximum HP for all of the monsters instead of their average as shown in the monster manual. And the players barely have any magic weapons.

Last session, the players leveled up to 4, and fought a CR5 monster (a revenant) with three ice mephits (CR1/2) and while it at least took longer than 2 rounds, it still wasn´t really a challenge.

 Are you following the Adventuring Day principle? One encounter per long rest will never be a challenge. 6 in a row will.