Using 10Mb Ethernet with 1Gigabit switches

I've been playing with a couple VaxStations and a qbus PDP11 recently and have been having trouble with connecting 10Mb ethernet to 100Mb and 1Gb switches. I have several 10base-T transceivers that I use since all my 10base2 hardware is in storage. Today for example, I connected a DELQA in the PDP11 to a 10-100-1000 switch and it did not work. I got out a 10-100 hub and put it between the PDP11 and the switch and it worked fine. Another example, my VS4000/60 netboots fine, but NetBSD will not detect the network interface unless it is connected to the "right" switch. All the switches and hubs I am using are from a collection of unmanaged consumer grade stuff (TRENDnet, ASUS, Linksys, etc.) that I have accumulated. Curious if anybody else has similar trouble when mixing old with new and slow with fast.