I have a base with a nether portal, and about 100 blocks away from that portal is a portal to another base. Almost every time I go from the first base to the nether to the second base, on my way back from the second base the game lags for 30-45s and the Switch reports a communication error.

This seems especially likely when the game is auto-saving, which is unfortunate because there are only about 5-10 seconds every hour when it's NOT autosaving.