The 401k plans are a primary retirement savings vehicle for employees. A 401k plan typically has an investment advisor, plan administrator, plan custodian, and pooled investment options. Each is paid a fee for the services they provide. With all the parties involved in the plan, have you considered how much your plan costs you each year? As long as a plan is not government sponsored, you do receive an annual cost disclosure where this information can be found.
You should closely examine this annual cost disclosure and decide if the cost for that current or former employer 401k plan is worth the limits it places on your investment options. Assuming your 401k plan is free because you don't write a check for the costs may cause you to miss out on better investment opportunities. A financial professional will help analyze what you do have and compare it to other options that could have better long-term benefits for your retirement.