DOS and MEV attacks are both issues that can impact the Ethereum network and result in gas-related problems.

A DOS attack typically involves a malicious actor flooding the network with a large number of transactions, rendering it unable to process legitimate transactions. This can lead to increased gas prices and delays in transaction confirmations. Essentially, the network becomes overwhelmed and unable to function efficiently.

On the other hand, MEV refers to the ability of miners to include, exclude, or re-order transactions in a block for their financial gain. This can result in the manipulation of transaction outcomes and can lead to issues such as front-running and sandwich attacks, ultimately impacting the gas prices for certain transactions.

Both DOS and MEV attacks can cause transactions to revert, leading to errors and gas-related issues. However, the root cause and mechanisms of these attacks differ significantly. DOS attacks focus on overwhelming the network's capacity, while MEV attacks involve miners manipulating transaction outcomes for their own benefit.