Hello @Jasonmurraynhrda,
We highly discourage the use of any inline cellular boosters/repeater/amplifiers, both @Joey_van_der_Gaag & myself have written previously on this within the forum. In Australia all cellular boosters/amplifiers are banned for very good reason, there is only one approved repeater brand in Australia (and many other parts of the world) though it dose not physically connect to your modems (this has been cover in many places previously).
There is an article in the Peplink Partner section of this forum going into extensive details on antenna selection, please ask you local Peplink Partner to send you a PDF copy and work through it with you, this is by far the better option than using any manufactures booster, you risk seriously damaging you modem (and warranty does not cover that damage) using these inline boosters as well as causing RF interference to the carriers network (in Australia fines start at $173,000 for individuals & over $200,000 for business).
If you are stuck with poor signal, ask Peplink to put you in touch with a Peplink Parter that has an RF/Antenna expert on the team.
Happy to Help,
Marcus 