Switches in Series, Newwork Setup GS108T

I have purchased two GS108Tv3 with the goal of keeping the computer at the end of the chain the fastest. My previous setup was Modem on one end of house connected to a router on the other end of the house in bridge mode then another router connected in the shop in bridge mode. In the shop is my primary computer that I want to be the primary for internet speed. All connections from the modem to the shop computer are wired with CAT 6 no wireless connections. We currently have 100mbps of service. Router setup was before I knew mesh was available and works for our wireless needs.

I recently purchased two GS108Tv3 to be able to set the priority on to control speed of aux items. Now I have the CAT 6 wired from the Modem to the switch to the final switch then to the shop computer. Off of the each switch I have connected the router to the switch along with all items that were previously connected into the routers.

One router is a Linksys EA8500 router and the other a Linksys EA6350.

Few questions

When the switches are connected in series the last one says Standalone Mode and can not be accessed. Do I need a crossover cable instead of a standard cable? What is the best mode to be in this situation?

I have lost connectivity to several smart devices is there a easy way to get them back online without starting all over on adding them to the system?

Where can I find info on best way to configure this setup or improve it?

Thanks in Advacnce!