[j-nsp] EX4300 + EX-UM-4X4SFP, can it do 1000Base over fiber?

[Karl Gerhard]

Hello

I have an EX4300 with a EX-UM-4X4SFP Uplink module (with 4x SFP slots) and a dual mode SFP Module that supports 1000Base LX and 10GBase LR. When inserted into the EX4300 the SFP module is always in 10GBase LR mode. Is there any way to configure any or all of the SFP slots to 1000Base?

The official specs claim that the uplink module is dual-mode 10GbE/1GbE:
"Uplink Module Options:
Others: 4-port dual-mode 10GbE/1GbE module with pluggable SFP+/SFP optics"
https://www.juniper.net/us/en/local/pdf/datasheets/1000467-en.pdf

Also, there is this one guy on the internet (tm) who claims that he managed to force an EX4300 into 1000Base mode on the SFP slots.
https://forums.juniper.net/t5/Ethernet-Switching/ex4200-EX-UM-2X4SFP-module-support-1G-10G-or-all-port-4x1g-or/td-p/317240

Any help is highly appreciated.

Regards
Karl